What does Arm Panties mean?

Arm Panties meaning in Urban Dictionary

Those completely un-cool arm sleeves which were first worn by professional bicycle bikers since they drive from low valleys (hot temps) around foothills (much cooler). These detachable sleeves are rolled down to the wrist, or eliminated & held in a pocket.Lately, runners and all sorts of sorts of professional athletes (term used loosely) tend to be putting on these things. Very not cool. Whom the hell do you think you might be, Lance Armstrong??