The Goonybirds were a goofy, "cartoony" line of kits developed by Estes - "The zaniest flying freaks of the universe" (I think that's an original quote). Sport rocketeers have since been kitbashing Baby Berthas and scratch building their own 'Goonified' versions of their favorite kits and real rockets. Semroc has also come out with their own kits - the Groonies. For a better definition of a Goony, you might want to read this TRF thread. Yes, TRF has started an entire sub-forum to talk about the odd little critters. Man, there are so many cool rockets in there!
Here's my Goonball XL5, bashed from an Estes SpaceShipOne kit: