1) n. Lies about anything weed related, namely about how much you smoked or what you did while stoned.
2) v. To smoke a bowl while taking a shit.
1) Jim: One time, I smoked half an ounce to myself in one sitting.
Bill: Man, that's bowlshit!
2) "Man, I had to take a shit halfway through my bowl, yesterday, so it ended up being a half-bowlshit."
A cuss word used in the world of bowlers, often when a spare is missed or when somebody is telling an exaggerated bowling story. Interchangeable with bullshit.
Person 1: So, I got a 7-10 split three times in one game the other day...
Person 2: Oh, come on, you're bowlshittin' me.