From Longman Dictionary of Contemporary Englishmuck in phrasal verb British English informal1 TOGETHERto do your share of the work that is necessary in order to get a job done If we all muck in, we could get the whole house painted by the end of the week.2 SHAREto share space with other people with There are only three bedrooms. Do you mind mucking in with the other boys? → muck→ See Verb table
Examples from the Corpus
muck with• Marie, who is single, really enjoys mucking in with the lads. 