The phrase "goofy side" means the fun and playful part of someone's personality. It refers to when people act silly, funny, or do things that might be considered a bit strange or unconventional. Full definition
I also have a very goofy side to me as well. (doulike.com)
If you're more into the fun and goofy side of the macabre à la «The Addams Family,» then pick up a copy of Forrest Leo's debut. (bookpage.com)
It's a role filled with contradictory notes, allowing us to see the cabbie's cheerily goofy side as he chats up a Secret Service agent (Richard Higgs) or struggles to make connections with the females he obsesses over. (bullz-eye.com)