In a crowded situation, such as a bar, when two people try to make their way past eachother, accidentally rubbing their genitals against one another.

When a person falls with a long object directly under him, and said long object impacts person in the crotch, causing extreme pain. Typically occurs to skateboarders.

When one passes a spliff once they have smoked it to the roach.

when 1 person (typically male) runs full force into another person who is sitting down, thus hitting the person in the face with their crotch

(n) (adj) (v)
a crotch is someone or something that is disgusting and makes you regurgitate on the floor. somehow it can be used as every single part of speech. if something is rude and appalling, they are crotch.

It's a special part that we all have down there.

Hiding the weed (or another drug)