Well I'd say it depends what kind of game you guys have. If it's COD like in some of the comments I can understand. But in my office we mostly play goofy party game, I sometimes invite my gf over to play with us and she manages to have fun while not being a gamer as well. Here's a list I made:
So far we've really enjoyed:
* speedrunners
* towerfall
* blazerush
fun:
* lovers in a dangerous spacetime
* overcooked
* miner warfare
* clusterpuck 99 (sucks if you're not > 4)
* hidden in plain sight
* Magicka
that were fun, but got boring fast:
* duck game
* CMYW
* trine 2
* starwhal
* Nidhogg
* Porcunipine
Meh:
* Castle Crashers
* Mount your friends
* Gangbeast
* Hammerwatch
* Screencheat
* ibb & obb