0 used when you are speaking about something or someone whose name you can not remember:
I need a - a whatchamacallit - one of those things that you can caramelize sugar with.
1 (used when you cannot remember or do not know the name of something) an object:
My whatchamacallit is broken – the thing that controls the oven temperature.
The -ma-, however, without question, seems to be the same interfixal -ma- in whatchamacallit.
Marines often use it in conversational tone as an alternative to mentioning widget or whatchamacallit.
