the act of falling off of a height and landing, anus first, onto a fence post, steel rebar, or the like. the name refers to a popular dairy queen frozen treat in which a stick is stuck straight into a dallop of ice cream.
did you hear the story of the guy who jumped into a ditch full of water and dilly-barred himself on a fence post? dude now shits out of a hole in his neck.
When there are two males and one female, the female first gives oral to the first male. Who ejaculates in her mouth. The female keeps it in her mouth while giving oral to the second male. Effectively coating his dick like a dilly bar.
"dude, we should totally give her mom a dilly bar"