A sex act in which a guy rubs his pecker back and forth between a woman's labia without penetration.
The woman's pussy is the bun and the guy's pecker is the weiner.
When you have a girl get on all fours, and you then put your penis on her neck. As she lifts her head up she'll create a "bun around your hotdog" and you proceed to fuck her neck.
To lather your dick in ketchup, mustard and fried onions before inserting inside the vagina thus creating the snatch into a bun. This can be seen as a pleasurable act or a punish sourced one for example if she didn't wash the dishes correctly.
When a man is giving oral to three other men. Two of the men are flaccid and uses their flaccid cocks as a bun for the third man, who is erect. The fourth man then sucks all three cocks
Ken invites Paulie, Caleb and Lucas over to enjoy some hot dogging. Paulie and Lucas call being the buns, which means Caleb is the hot dog. Ken puts some ketchup on and goes to town