Having started the engine on a cold winters day and waited for it to warm up a radioed my intentions. no reply, so tried again. no reply, and again. Looked at the frequency, thought that's not right, then had total brain freeze and couldn't remember it so had to shut down, unstrap and go back to the club house to ask for it.
once got to about 50ft on approach and realised the gear was still up...
sure there are others, if I could remember them!