Compare whatchamacallit with other words:
jiggambob vs. whatchamacallit
oojamaflip vs. whatchamacallit
whatchamacallit vs. whatshumacallit
gadget vs. whatchamacallit
gimmick vs. whatchamacallit
whatchamacallit vs. whatnot
thingamajig vs. whatchamacallit