Free balling

[Sarah]

walkin around, usually in shorts, without underwear on. often sung along with, and popularized by, the tom petty song free falling

[Mark Zuckerberg]

The act of wearing pants without underwear, allowing your balls to hang freely

[Sarah]

a Male individual who wears no underwear

[Mark Zuckerberg]

When one wears no underwear beneath his trousers
e.g Did you see Steves arse, he was free balling so hard.

Or, In the sport of cricket one is said to free ball when they wear no box (protects genitals) whilst batting.

[Sonia]

When a guy doesnt wear anything underneath his pants/trousers/shorts and he is letting himself hang loose.