Here are a few that are probably a bit older and maybe way too easy but I thought I’d share anyway...

The one who makes it sells it.

The one who buys it never uses it.

The one who uses it never knows he’s using it.

What is it?”

What has a head, a tail, is brown and has no legs?

What always runs but never walks,

often murmurs, never talks,

has a bed but never sleeps,

has a mouth but never eats?