What is Double-barrel?
1.
Used to describe a large, ugly chick. If one came after you you'd have to shoot her with both barrels of a shotgun to save yourself.
The party was pretty cool, but was filled with double-barrels.
See
2.
For two men to fill both a woman's barrels, so to speak.
On special occasions, Melinda enjoyed being double-barrelled by Fred and Bill.
See