What's white, sticky, and better to spit out then to swallow?
Toothpaste.
What's white, sticky, and better to spit out then to swallow?
Toothpaste.
The joke uses the setup of a riddle to create a silly situation. The answer, toothpaste, is something you're supposed to spit out, playing on the gross-out humor of swallowing something that tastes bad.