A slang term for a penis. This was invented by many rappers/hip-hop artists throughout music history. It is usually used in the context "beat her with a wiffleball bat." or other variants such as "brought my wiffleball bat."
Girlfreind "Hey, wanna come over?"
Guy "I'll bring my wiffleball bat."
Girl "I can't believe you cheated on me! Were over! "
Guy "I'll beat you with my wiffleball bat, bitch!"