When one waves hello or goodbye, the fat on their arm may appear to flap in a waving matter as well. Most commonly seen on obese people and mothers.
Soccer mom: "Have fun at soccer, Jimmy! I love you!"

Jimmy: "Okay mom, I love you too!"

Friends: "Man. Jimmy, your mom has some serious bye-bye arm."
by Nosredna Ekul August 5, 2009
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the back of your upper arms that keep swinging after your doe waving good bye becuase they are so fat & n muscle is there
"I hate My Bye Bye Arms"
by Liz March 27, 2004
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