Definition: In this task, you are given a Reddit post as a text. Your task is to generate a title for this text. The title should start with "TIFU by", followed by a situation that caused humor. The title should contain 7-12 words, ideally.
Input: Text: a few weeks ago the janitor at my workplace found a loaded handgun hidden in the trash can in the bathroom. i work in a plasma donation center in a pretty shitty neighborhood, so sketchy people are pretty common. this really scared my boss, so she decided that we need to vamp up security by hiring off-duty cops. their presence has the donor's on their best behavior, but hasn't really affected our staff's laid back nature. we work hard but we also have fun. we are constantly pranking each other and joking around. 

well, today i was working in the lab when i saw a co-worker of mine getting ready to leave. he walked to our office to clock out and decided it's been a while since i've messed with him. he came back through my area and i heard him go into the bathroom. i ran around the corner and decided it would be hilarious to pull on the door handle as he tried to get out. i waited by the door and as soon as i heard the toilet flush, i pulled with all my strength. i felt him pull for a second and let go when it wouldn't open. he tried again and nothing. i was trying my hardest not to laugh out loud when i heard him say "what the fuck" as he tried to pull it open once more. i heard him a let out loud sigh and i took that chance to run back into the lab. i heard the door swing open just as i turned the corner, hopefully out of sight. 

i tried to compose myself and pretend i as working, but the shit eating grin on my face was a dead giveaway. i heard his footsteps as he approached the window by my workstation. i knew the second he looked into the lab i would bust out laughing. i didn't laugh though. the second the cop came into view i felt my heart go into my throat. he looked me in the eyes as he walked by. he didn't say anything. i didn't say anything. but he knows.

TIFU by trapping someone in the bathroom.