So like, anal...

Okay well this is embarassing to me but obviously some guys wanna do anal. I never have, it scares me. I have a fear that I'll poop all over him coz in MY head i see anal as like... Plunging a toilet. But, i do wanna try it once but i know it's going to hurt really bad. Any advice? I'm sorry guys, I'm really curious and kind of very embarassed.