To hang up on (a nail, hook, wall, etc.); to reach or get s.t. by means of hooking it with s.t. else; to accidently get hung up on s.t.; to get snagged on s.t.
The -un imp. focuses on the object one is trying to reach by hooking. The -an imp. and the pa--un imp. focus on the object one is hanging up.
The reason I fell was because my foot got snagged in the vines.
Hang my fish up on that nail.