Spectacularly nerdy sexual roleplay.
Though we didn't get to see it (perhaps thankfully), The Good Wife flirted with dressing up as American revolutionaries. Which is, first of all, weird, and second of all, really difficult to imagine the mechanics of. But I imagine it being a bit like this:
Then, on a late season three episode of Parks and Recreation, we overhear a deliciously disturbing phone message that Ben and Leslie accidentally left on Ron's phone, where we learn that she plays Thatcher and he plays Reagan.
Feel free to share other instances of weird roleplay in the comments (let's keep it to television).