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1.
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 26, 2004
 
2.
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 04, 2009