Elusive rocks found on the shores of lake Huron. Legend has it if you find a rock with the word sex etched into you can exchange the rock to anyone you wish for sexual favors.

when you're hungover as shit after a spending a night drunk as a skunk

Just another fucking rock

Any large rock. A sex rock is often found around a house in the landscaping. A sex rock can be any shape but must be large enough to have intercourse on.