Hand me the whatchamacallit

Meaning

A convenient placeholder term used when the speaker has completely forgotten the name of an object or simply cannot be bothered to retrieve it from memory. It implies that the listener should be psychic enough to know exactly what item is needed based on context clues.

Casual, forgetful, exasperated

Used in a sentence

• Hand me the whatchamacallit so I can tighten this bolt.
• I cannot find the whatchamacallit, so I guess the project is on hold.
• Just pass me the whatchamacallit on the counter, honey.