When a chick (accidently) touches you with her boobs.
Guy: That chick just totally ground rule double'd my shoulder for a good 5 seconds.
Copping a feel on a girl without ever making out. Most commonly occurs at parties or dance clubs. Named for the circumstance in baseball when a player hits a ball and it bounces over the wall. He automatically advances to second base.
Person 1: Dude, did you see me grabbing that girl's tit when we were dancing? I totally just got to second base in like 5 minutes.
Person 2: I'm not sure if that qualifies as second base. It's more like a ground rule double.
Having cyber-sex with your significant other. This is referred to as a ground rule double because even though you may think you are going pretty far, you can ultimately only get to second base.
Eric: "How did your Skype conversation with your girlfriend go the other night?"
Sean: "Ground rule double every time bro!"
When with a women you start off by swinging for the fences but something happens to where you are forced to stay at 2nd base.
"I was with this hottie last night, but my brother kept walking in the and out of the roomie, so instead of a home-run, I got a Ground Rule Double"
When a guy finds himself in an unclear sleeping situation with a woman, he is entitled to "take second base" without comment or condemnation.
Guy #1: "Yo, I heard that (insert female name here) crashed in your bed last night."
Guy #2: "Yeah...nothing happend."
Guy #1: "What? You declined a ground-rule double!"
Guy #2: "Shit! Did I really?"
Guy #1: "Yeah, you were definitely entitled to boobie touch-age."
Similar to an Upper Decker, except you 1st lay a turd on the toilet bow lid. You then remove the lid from the upper tank and rapidly fling the toilet bowl lid into the open position, catapulting the turd into the upper tank. This is worse than an upper decker, because not only does the owner have a turd to fish out of the tank, but they also have a lid that requires cleaning as well.
Q: Why is their poo on the toilet lid?
A: Damn it, someone hit a ground rule double before they left our party!
Jacking off while you take a dump.
I almost hit 3 ground rule doubles last night!