Verb - Act of raising ones arms and open hands in the air as to convey to anyone within view at the time "WTF?!" or "WTF are you f'ing doing?!"
WTF Arms are most commonly displayed when people make dick moves that offend oneself in driving situations. Often accompanied by a slightly open mouth and nodding ones head once to each side.
John: The prick in the SUV slammed on his brakes for a f*cking squirrel while we were going 40mph. WTF? I gave him the WTF Arms and passed him - douchebag.
April: The finger is classic, but the WTF Arms are good of when kids are around.