Noun. The extra fat and skin that hangs down and jiggles while waving. Plural: hi bettys.
As if you were waving to your friend and saying "Hi Betty".
by dsignbob June 10, 2008
when a person's upper arm has too much fat and it jiggles all around when they wave at somebody (as if an old lady was waving to Betty)
i sat next to my grandma at church and when she waved to her friend one of her hi-betties smacked me in the forehead
by kalisha July 26, 2007