here is an interesting British slang word for a "what's it's name": oojah

[tugging forelock emoticon]
I haven't heard "oojah" used, but have heard "oojah-ma-flip", "thing-a-ma-jig" "thingummy" "thingummy-bob" "wassisname" "whatchamacallit".
And I learnt the very useful French (possibly Swiss French) phrase "machin-truc-chose" which effectively means "thing-thing-thing"

Rod Ward