A smudgie is when you freeze a length of your shit, and use it as a dildo on a girl.
Wouldn't it melt I hear you say? That's the smudgie part.

Schoolboy slang (especially boarding schools in Australia): The act of wiping one's spread bare arse and "brown eye" on someone or something, thereby leaving a smudge.

A frozen desert or snack consisting of a mix of banana and peanut butter, sandwiched between two graham crackers.

The act of putting your foot against the fence and raking downward over a hole that a dog has it's nose in.