muck about
verb
RareNot in standard dictionaries
1
To do random unplanned work or spend time idly
2
To attempt to do something with a piece of equipment without understanding how it works.
3
To be playful; full of fun and high spirits; to treat a situation unseriously.
4
To play with; to toy with; to waste the time of (a person).
Thesaurus
#informal