On a Wednesday - don't judge.
A Wild-West themed card game we picked up on sale at Target - this game has an INSANE amount of rules. But it's really simple to follow once you start playing. We usually have an average of 6 players, and the rules change based on the amount of players you've got. Basically - everyone's given a role and an objective to play towards and you play to achieve that objective. The objective is different for each role (Sheriff, Deputy, Outlaw, Renegade) and you've gotta figure out who's role is what and work together to achieve your objective. Its super fun, and every time we play we enjoy the hell out of it! Also, it's fun to shoot your friends.
We have expansions for this, but just the base game is enough for a party of 6 to play and yell at each other for an hour or so. Another card-based game it's basically a board game RPG where you create a character using race and class cards, and then equip items and defeat monsters. Best part about munchkins, you can "help" either the person attacking a monster or the monster itself. The gameplay has a pretty simple structure and is quick to pick up, although the more finite rules have us scouring the rule book and finally just asking the owner of the game their opinion (as per the rules, they have final say).
This one is new to both our collection and the world. The game is basically cards against humanity in picture form. Same "card czar" gameplay and basically you make 3 panel cartoon strips. Whoever the card czar thinks is the funniest/best - wins the round. You can play to whatever you want and it's fun. Its pretty easy for anyone to pick up and play and is perfect for those who are politically incorrect and aren't seasoned more complicated tabletop games.