Terrain Building
Terrain building is an erotic gay act involving small, sharp shards, a funnel, and a man's gaping ass. The material is poured into the hole, then the procedure is repeated on the other partner. The materials used vary based on the couple, with aquarium gravel being the most common. Other common materials include glass, sand, and circuit board pieces.
Josh and Mark were terrain building again last weekend, they still both can't walk right.