Twice as effective as a double dare, which is twice as effective as a dare.
Anthony: I dare you to lick a tree.
Franklin: Yeah, well I double dare you to lick a tree.
Billy: I DOUBLE DOGGY DARE YOU TO LICK A TREE.
*Anthony and Franklin then proceed to lick a tree*
Sexual position where the guy bends over in front of the girl and sticks his dick back through his legs to fuck her.
Me: I heard Paul fucked some chick reverse doggy style last night.
Justin: Really? I didn't think his dick was big enough for that.
Me: You're probably right. He's a liar.