Not quite a double date, but
not exactly a date either. It's when you invite someone out on a date, and they pull a defensive maneuver and bring a friend along, as a date
shield.
Dude, I asked out that hot chick Sally on a date Saturday to cool party. She said yes, because she knew it was a cool scene, but she
turned it into a
one-and-a-half date, bringing along her BFF Tina to
cock block.