The thing I find fascinating about the phrase “slow clap” is that it's used to refer to two different things that are near-opposites in meaning.
On the one hand, there's what TV Tropes calls the Slow Clap, wherein someone starts clapping slowly, the whole crowd gradually joins in as the pace quickens, and it ends with wild applause from everyone.
On the other hand, there's what TV Tropes calls Sarcastic Clapping, wherein someone (usually one person) claps slowly and sarcastically.
TV Tropes gives the two things different names, but the illustrative quote at the beginning of the Sarcastic Clapping entry uses the phrase “slow clap.”
Urban Dictionary demonstrates the same contrasting usages of the term.
This wouldn't normally be particularly notable. There are lots of things that are said or done sarcastically to mean the opposite of the surface meaning.
But the reason I'm posting about it, and posting here in my words/language blog rather than elsewhere, is that recently I've seen the phrase used fairly often on the Internet. And it's often unclear which of the two meanings the writer intends.
I usually see it in a comment on a blog entry or similar posting. The entirety of the comment is usually “Slow clap” or “Slow. Clap.”
I suspect that in most such cases, the commenter doesn't realize that there are two opposite things that the comment could mean. And to be fair, in some cases it's pretty clear; for example, if someone posts about some wonderful awesome thing that someone has done, then probably a “slow clap” comment indicates actual applause rather than sarcastic applause.
I suppose this is arguably just one more example, among thousands, of the difficulties of detecting sarcasm in written communication. But it seems different to me.
Perhaps because in movies and TV shows, if a single person does a slow clap, it's almost always the sarcastic kind. So if one commenter writes “slow clap,” the mental image I get is not of a crowd of people starting to applaud slowly and then picking up the tempo.
Also, the reason that the positive kind of slow clap starts out slow is generally that the audience is (for example) hesitant or chagrined or uncertain, or sometimes embarrassed on the applaudee's behalf. So it's not the “slow” part of it that's an accolade. So it seems odd to me to say “slow clap” rather than just “applause” in a comment that's intended to be positive; the slow clap tends to suggest to me that the clappers start out with some reservations. Otherwise it would be just a regular clap.
Anyway, I'm not trying to be prescriptivist about this; clearly, people do use the written phrase “slow clap” to indicate approval. So this entry isn't meant to criticize that usage, but rather to document it, because it surprised me when I started seeing it.