One of those tricky things

So we just had to deal with a case of [thing which gives me a serious case of the squicky twitching meemies].

As it happens, I am aware that this thing also gives about half of you folks the squicky twitching meemies.

Therefore. Please make nonspecific soothing noises at me?

(I feel like I shouldn't even have to say this but if you comment trying to guess what it was, I'm going to assume you don't value your commenting privileges.)