Gallagher's Hammer
Your penis's name when you're doing the breaststroke on a girl's chest.
My Gallagher's Hammer was doing the breaststroke like it was a swimming competition.
He had his Gallagher's Hammer doing laps on her chest like it was a pool party.
She called her Gallagher's Hammer 'The Swimmer' because it was going back and forth nonstop.