Why do i say really really stupid things when around girls?

i was at kickboxing earlier and while we were putting our things away id noticed id lost my boxing gloves,when i found them a nice girl sed why dont you put your name on them and me being me sed in a retarded spastic voice "oh put my name on these like a spastic uuuuuuuuuuuu"i think its safe to say the girl was not amused...why do i say stupid things WWWHHHYYYYYYYYY