Pulling a Brian occurs when a male seems very interested in a girl, pursues her for a decent amount of time then randomly decides that the girl is no longer worth it. The male then leaves with the excuses of "I am not ready" or "I haven't gotten over my past girlfriend." It usually occurs a month into dating.
When a full-grown individual shits his or her pants.
"Ah man, I thought I was just going to let out a juicy fart, but I ended up pulling a Brian."
missing in action (MIA) for hours or days at a time
not answering calls and or falling asleep when you have made plans, thats pulling a brian
When a person falls off and or gets hurt on excersize equipment.
"dude, I went to the gym and watched a man falling off a tredmil, pulling a brian"