In baseball, you can swing for a hit, or try to bunt for a hit. Usually bunting is done as an intentional sacrifice play, but there certainly are speedsters out there taking advantage of infielders playing deep and dropping one for a hit.
Even when there is a man on base, there is even the option for discretion on the part of the official scorer to give the batter an out instead of a sacrifice (i.e., an at-bat that counts for diluting his batting average statistic) if he feels the batter was not truly attempting to give himself up, but was trying for a hit.
Yet just moving into bunt position does not count as a swing. The bat must still cross the plane of the front of the plate, just as a swing attempt would, in order to be called a strike (if the pitch itself was not in the strike zone).
There are also “swinging bunts”, where a player checks his swing midway or simply makes very incidental light contact and puts the ball into play weakly.
And yet, the rules of MLB make one curious (to me) special exception for bunts. If he bunts a ball foul, it counts as a strike just as it would for any other batted ball. But once there are two strikes, a player can swing and foul off as many pitches as necessary until he records a hit or an out (see: Mookie Wilson, 1986 World Series Game 6), but bunting foul with two strikes is a strikeout.
Why is this? Most “special case” rules in baseball were created in response to some perceived imbalance in the game. The infield fly rule was created to address the possibility of intentionally dropping a pop-up to get an easy double play. The “balk” rule was created to prevent the pitcher from “deke-ing” the baserunner (we’d basically never see a stolen base attempt). But why penalize bunting?
It’s not like it’s any easier to “bunt foul forever” than it is to swing for foul balls forever, and why would a batter intentionally bunt foul forever? (Was that ever done in the early days, by Ty Cobb or some other skilled but assholean player, to wear out the pitcher?)
If the idea is to discourage sacrificing (which seems odd), and there is already a judgment distinction being made between sacrifice bunting and bunting for a hit, then shouldn’t one be allowed to bunt foul with two strikes IF it’s clearly a bunt hit attempt (for example, if there’s nobody on base)? On the flip-side, if it really is a rule to make hitters take “legitimate” swings, why make a distinction between a swinging and “true” bunt attempt?