In the original Borderlands, you can jump on to the heads of NPCs and other Player Characters.
Once you are on top of someones head, you'll sort of keep bouncing up and down, you can't really "stand" on their head.
We used to keep a stopwatch and see how long one of us could bounce for, before falling off. It's been so long I don't even recall our best record.
However, it was one of the dumbest and funnest things we ever got up to in Borderlands.