From Longman Dictionary of Contemporary Englishmoon about/around phrasal verbBritish English informalLAZY to spend your time lazily, moving around with no real purpose I wish you’d stop mooning about and do something useful! → moon→ See Verb table
Examples from the Corpus
moon about/around• Is that you mooning about again?• Sometimes it's so they can moon around and say how beautiful it all was and pretend they're still lifers there.• You did not moon about love.• She was still mooning about the theatre, gazing at him.• But there was no point in mooning around until then.• What good can you do mooning around worrying, picking at your food like an anorexic, and giving yourself splitting headaches? 