whatchamacallit

noun

1. (colloquial)A metasyntactic term used for any object whose actual name the speaker does not know or cannot remember; a doodad, gizmo, thingamajig, thingy.

   “The Thingamajig and the Wachamacallit.”

   “You’re—you must be the whatchamacallit, huh? The peer.”

   “JESSICA: How many times do I have to say it? We were not stealing, Officer. We were just— / MONAHAN: I know. Performing some kind of whatchamacallit deed. Anyhow, they go to the clink, that's what happens to people who filch city property.”

   “I'm a boy, so when I'm sick, they can call in poohaghooma, Indian doctor. But not Tom Mitchell! No, sir! [We] won't have Tom Mitchell to doctor me! 'Cause whatchamacallit, he always used to doctor me …”

   “"Think we ought to check this whatchamacallit?" / "No, that doodad over there seems to be the problem."”