Ool was the cavespeak word for food in the 1981 comedy Caveman, featuring Ringo Starr. Some regulars at Chicago's Thursday adopted it as a codeword to describe going out to eat after meetings, usually at a 24-hour deli called the Belden in West Rogers Park.

The question, "Ool?" or a secret sign were delivered surreptitiously so those in the know could sneak off without including certain deadbeats known to skip out without paying their full share of the check.