When someone is bad at throwing a ball in sports.
"Nice throw, custard arm."

"What is Jono doing, he's got the biggest custard arm ever."
by Jono P. November 25, 2005
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Having fat arms, the fat usually hangs from the arm - the same as lunch lady arms
Man, check out that fat piece of shits custard arms
by pezzzzzz October 21, 2009
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