When a person (usually one who is of the straightedge lifestyle) refuses to let a fellow pothead (or potheads) light a bowl/rip a bong/hit a blunt/puff a joint because they insist that "zomg sm0k!ng iz n0t coOl guyz", therefore leading to a very dissatisfying afternoon without the presence of marijuana. The person who is blocking the bud (the budblocker) will continue to make the people who want to smoke (the budblockees) feel bad until the budblockees give in and have to resort to smoking at home. And then watching The Science of Sleep and/or Eternal Sunshine Of The Spotless Mind, and talking to the other budblockees on AIM.
Budblockee #1: Check out this new strain I got. It's called Juicy Fruit Tropical Sour Diesel Juicy Diesel Fruit White Widow Northern Lights Kush Purple Haze laced with speed, acid, meth, ecstasy and coke. Let's smoke this shiz!
Budblockee #2: Fuck yeah. Now that the SATs are over Imma smoke errrrrrday FUCK THE REGENTS!
Budblocker: Come on guys, don't smoke, you guys get really boring and smoking is gross. I feel like I just talk to myself because you guys are so unfocused wait is that an unopened can of budweiser on the floor? Mine!