Not at all serious (2,3)
I believe the answer is:
in fun
(Other definitions for in fun that I've seen before include "As a joke - not seriously" , "to raise a smile?" , "Not intended seriously" , "for a laugh" .)
I believe the answer is:
in fun
(Other definitions for in fun that I've seen before include "As a joke - not seriously" , "to raise a smile?" , "Not intended seriously" , "for a laugh" .)