2. The act of putting forward an idea to one's bros.
Brent: "Oh it was rad dude, Chad totally broposed"
Dirk: "Wow that's awesome dude, i'm totally happy for you two"
2. (Dirk gets up at the table)
Dirk :"Gentlemen, i wish to bropose something, we should totally have a bro and sack night at mine this friday"
All : "What an excellent broposal"