"A placeholder name is used to refer to an object whose name is either irrelevant or unknown in the context it is being discussed. These placeholders typically function grammatically as nouns and can be used for people (John Doe), objects (Widget) or places (Timbuktu). They share a property with pronouns because their referents must be supplied by context."

Some folks even call them "kadigans", although if you're going to use a word like kadigan you might as well just use doohickey in the first place.

German is more sophisticated in this respect, I find. The Germans tend to speak so precisely that they don't usually have to resort to this kind of nonsense. They do, of course (try Dingsda, Dings, Dingens, Zeug,Zeugs, Klecksdorf, Kuhdorf etc.), but not nearly as often as English speakers do.

We revel in it, of course. You probably don't really want to know how many thingamijigs and ealies you've spit out over the course of your eventful lifetime. But it could be worse (and may actually be). Just think of that foul-mouthed acquaintance of yours who's obsessed with the f-word (and I know you've got one). Talk about a doohickey! How vulgar, I mean, popular. The f-word has to be the most versatile of all placeholders there are because, as we all know, it can be used in all the grammatical forms mentioned above - and usually is. If the folks doing the cussing know what they're doing, that is.

Or should I say, if the f-folks doing the f-cussing in bum-f or wherever-the-f they might be are any f-good at any of this f-stuff. Oh! F-stuff there reminds me that we also like to use the s-word as a placeholder, too. As if you didn't know that already. Come on, now. A little variety now and then never hurt anybody.