Somtimes they're a little busy...
Overheard inbound to EAA's AirVenture, Oshkosh, 2003, where only the controllers on the ground speak and pilots respond by rocking their wings.
Controller: Bell Helicopter, Fisk Approach. If you read, rock your wings.
Controller: Right... OK, I guess you really don't have any wings. Bell Helicopter, if you read, transmit.
Helicopter: I read you, Fisk.
Controller: Roger, enter left traffic for runway 36, welcome to Oshkosh ... you've earned your wings today.