What about that zipper icon?

Hint 1 of 5:

Normally it adjusts your clothing.

Hint 2 of 5:

Ah, that feels better.

Hint 3 of 5:

It is also good for lighting matches, but...

Hint 4 of 5:

Try unzipping in the right place.

Hint 5 of 5:

Like in front of a toilet bowl.