Grammar Corner

This week's Grammar Corner features the words "that" and "which" and when they should be used.

Basically, "that" is used restrictively and "which" is used nonrestrictively (although "which" can be used restrictively in some cases, to be explained later).

You want to use "that" when you're trying to narrow something down or identify one particular thingamajig. Here are some examples:
"I only want a girl that has ginormous titties."
"I fucked that big muscular guy standing over by the bathroom door."

You want to use "which" when you're trying to add something about something already identified in the sentence. In this case, "which" is usually preceded by a comma, as in these following sentences:
"The older gentleman was followed closely by a twinkish guy, which is hardly the BDSM partner he would normally go for."
"Her wet pussy smelled like fluoride, which is a smell that should hardly be associated with that region."

Now, "which" can be used restrictively, but only if it's preceded by a preposition. Since it's being used restrictively, no comma is needed, as in "the pudding in which I dipped my balls" or "the loose vagina in which my double-headed dildo was found."

These rules, of course, don't matter in England, where they could give a rat's ass whether you use that or which correctly. Bangers and mash to 'em!

Source: Secs. 5.202, Chicago Manual of Style, 15th ed.