No urban dictionary jokes, please.
I'm talking about the ones that hang off your bicycle saddle! A recent post on this subject left me wanting a fuller discussion without robbing the OP's thread too much. I'm moving away from big saddlebags and into handlebar bags, with front panniers for touring, but there's something quite nice looking about a bike with a goodly sized saddlebag. Makes one want to wear tweed, sit upright, and smoke a pipe.
There's the small, tube, patch kit, and a few tools variety. I don't have one this size anymore, and let's just say if you post a pic, it should be your bike.
You've got your smaller type bags, about a liter or two capacity:

Velo Orange Croissant

ditto
Then you've got your medium bags:

Minnehaha Medium

Zimbale 11 liter
And then you're beyond bags, let's just call them trunks, shall we?

Sackville
Medium - they make a large, which is big enough to store a small framed bike in, or can be used as an apartment in San Francisco in a pinch.