Doonesbury by Garry Trudeau for July 24, 2015

Does it involve inflatable toys?

Quickie?

eating quiche?

Don’t think it’s playing quoits.

Who drank Boopsie’s wine?

Some would consider that depraved, if not verboten.

Q-Bert!

Quilting?

Well, it isn’t quidditch.

That is also one that occurred to me, but I think my first guess is more likely.

I feel so dumb for not figuring out the"Q" word — but it looks like I’m in a lot of company! Com’on, guys, can’t you give me another letter?

Quibbling! Except you can do that anywhere, even on the Internet.

“Q” and in the shallow end of the pool? That is some sick and twisted 5h1t right there.

Obviously it’s the most depraved form possible of quacking like a duck.

Quiff?

Since real men don’t eat quiche, it would involve a quiche somehow…

Hey everyone, check out the Urban Dictionary website for Australian quoits.

I got it! Quimby!

Quoitus?

Quaid. Possibly Dennis, probably Randy.

Was Quentin Tarantino around then?

Obviously quaalude.

quaaludes? Popular at the time, topical again

Pointspread beat me to it, quaaludes were the drug of choice back then, but you almost never hear of them anymore.