Baseball has several "unwritten rules" that you may don't know about, probably because they are - follow me closely here - unwritten. I'll give you an example.
Remember that game in 2011 when Jared Weaver threw a fastball at Alex Avila's head because Carlos Guillen had just "pimped" a home run in the previous at-bat, because Weaver had barked at Magglio Ordonez a few innings before after he (Weaver, that is) felt like he (Ordonez, that is) had pimped his home run too much, when really he (Ordonez, still) was just looking to see if it (the baseball, I mean) was going to be fair or foul, but the real issue was that he (Weaver, I think) was really suspicious that she (his [Weaver's] girlfriend at the time) was maybe cheating on him (Guillen, don't ask me how) with you (meaning, me).
Let's start over.
That incident illustrated several unwritten rules: a) you don't pimp your home runs, but b) you also don't gripe at a veteran of the game or c) that veteran's teammate is obliged to retaliate - still, d) if you do pimp a home run, you can absolutely expect the pitcher to retaliate against you or e) another member of your team, so the most important thing - as illustrated two paragraphs ago - is f) be careful how you use pronouns.
Here are seven of those unwritten rules, carefully selected, distilled and possibly distorted from Jason Turbow's excellent book, The Baseball Codes.
1. Thou Shalt Not Steal in a Blowout
If your team is ahead by a bunch of runs (I believe five is an acceptable starting point), it's considered disrespectful and rude to steal bases, because then you're just piling on, you inconsiderate poop-head who obviously just wants to ensure a victory. Come ooonnnnnnn, give the other team a chance!
2. Thou Shalt Not Pimp Thy Home Runs
See the Ordonez/Weaver/Guillen incident above. Or consider the hilarious incident from last year, when the Brewers' Carlos Gomez pimped a home run against the Braves' Paul Maholm, and catcher Brian McCann actually blocked home plate by standing in the third base line to confront Gomez when he arrived.
It later came out that McCann was so upset because he had Maholm in his fantasy league, but it still illustrates the point. It's considered un-sportsmanlike to celebrate your little personal "wins" on the field too much, whether that's standing in the box to admire a home run, clapping and yelling as you round the bases, or having graphic sex (consensual or otherwise) with the pitcher's mother right there in the dugout afterwards.
3. Thou Shalt Throw at Batters or Teams that Pimp Their Home Runs
This is the corollary to the previous rule. An uncalled for pimping is an affront not only to the pitcher, but also to the pitcher's team, so everyone expects the pitcher to retaliate at some point, and by "retaliate" I mean "a grown man intentionally throws a baseball as hard as he can directly at another grown man."
He might target the very next batter (which is acceptable), or he might wait a few innings and target the Offending Pimper directly (also acceptable). If the pitcher is removed from the game before he can retaliate, he may wait weeks, months, or even years to get his revenge. Do a little digging into the Roger Clemens/Mike Piazza affair (which included Clemens throwing a piece of broken bat at Piazza) and you'll find that it lasted at least a couple of years. (This is not strictly an example of home-run pimping, just an example of retaliation that can go on for years, and involve multiple people.)
4. Thou Shalt Always Join Thy Teammates in a Brawl
This one probably goes without saying, and yet I'm going to pad my word count by saying it anyway. If two opposing players end up "going at it," the benches must clear. You must always, always, always defend your teammates, even if it's not your squabble to start with, and players who opt out of a bench-clearing brawl may find themselves the target of retaliation - by their own team.
This is why even the bullpens empty during an on-field scuffle - not showing up to defend your team is baseball treason. Turbow relates the story in his book of a brutal brawl between Eric Davis (Cincinnati Reds) and Ray Knight (New York Mets) during a game in 1986, a brawl which Mets outfielder George Foster decided to skip. He sat on the bench, because a) he didn't want to get hurt (the selfish bum) and b) he didn't want to promote violence in baseball. He was thinking of the children! He was also released from the team within weeks.
5. Thou Shalt Steal Signs on the Field
Really, it's acceptable, and maybe even expected. Members of the Tigers clubhouse have spoken with admiration about Miggy's ability, once he's gotten on base, to easily swipe the other team's signs within minutes. It's a skill that wins the admiration of teammates, and also - apparently - the opposition as well. Just as long as you don't pimp it too hard.
6. Thou Shalt Most Definitely Not Steal Signs at the Plate
This is the exception to the rule. If you can stand at second base as a runner and decode the catcher's signs, you're cool, but if you're in the batter's box, you'd better keep your bleeping eyes forward and not be glancing back at the catcher's hands.
Turbow relates a hilarious story about Jose Nunez's (Blue Jays) first at-bat in a 1988 spring training game against Philadelphia, during which he blatantly turned his head around to see what sign Lance Parrish (yes, that Lance Parrish) was giving the pitcher. Parrish blurted out, "What are you doing?", to which a very naive Nunez admitted, "I want to see the signs."
The at-bat carried on, with Parrish taking requests from Nunez ("A fastball ... that one was too fast, can I have a changeup next?") until Nunez finally grounded out, by which point Parrish, his pitcher, and the umpire were all rolling on the ground and howling.
7. Thou Shalt Not Speak of a Developing No-Hitter
You already knew about this one, right? Baseball players are super-super-superstitious. Jim Leyland was said to wear the same pair of underwear for as long as a winning streak was alive. Wade Boggs famously made chicken his exclusive pre-game meal, saying, "there's hits in chicken" - all because he had a four-hit outing after eating pre-game chicken one time. There are lucky hats, lucky gloves, on-field rituals, movements, maybe even blood sacrifices.
(I'm not saying he does, but Big Papi looks like the kind of guy who might eat a still-beating owl's heart before every game.)
In the midst of all of these superstitions and rituals is the most sacred of them all: mentioning a no-hitter while it is happening will immediately jinx it, it won't happen, and then Santa Claus will put coal in your stocking, you'll never find a leprechaun, and you'll be forced to wear Jim Leyland's win-streaked underwear.
I'm not saying there's any merit to this superstition, but I am saying that I've never seen a no-hitter come to completion after I've openly talked about it, so, QED? Better just to play it safe.