Well, every term in the computer world has some weird meaning, Flamingo isn't any different.  It was originally meant to be used in art classes (and has been), so here is the meaning.

When I was in college, I used to ride a skateboard to class every day.  Sometimes I would balance on one foot as I rode, just for fun.  My friend, who was studying art said, "You look like a Flamingo!" and one night sketched this picture for me.  So I adopted that as the name of the program and later on came up with the acronym. I taught computer art classes which used Flamingo as one of the tools.  I told the class what Flamingo meant and some people laughed, but not everybody.  One student whom I later became friends with said, "I disliked you the first few weeks after you told me what Flamingo meant."  I guess some people just don't have the same sense of humor as I.