Clowning around means that a person is acting like a clown or simply acting silly. It could also refer to the 1991 australian family film of the same name.
clowning around...
No Clowning Around - 2012 was released on: USA: 28 December 2012
The cast of Clowning Around - 2010 includes: Daniel Oser as Vizzo
Field Trip - 1997 Clowning Around - 2.1 was released on: USA: 1998
Spellbinder - 1995 Clowning Around 1-22 is rated/received certificates of: Australia:G
Field Trip - 1997 Clowning Around 2-1 was released on: USA: 1998
Clowning Around with Mary Jane - 2011 was released on: USA: 23 October 2011 (Sacramento Horror Film Festival)
Kenan and Kel - 1996 Clowning Around 2-2 was released on: USA: 13 September 1997
Barter Kings - 2012 Clowning Around in Utah 3-3 was released on: USA: 20 August 2013
It's not an idiom - it pretty much means what it seems to mean. That makes it a metaphor. Someone might not be an actual circus clown, but they're acting like one, fooling around and trying to make people laugh.
The cast of Clowning Around - 2012 includes: Lincoln Boling as Little Kid Bay Dariz as Mr. McCarthy Kate McKenna as The Babysitter Pancho Moler as Clown
It means acting silly in the hope of making your friends or others laugh.