From Longman Dictionary of Contemporary Englishpitch in phrasal verb informal1 START DOING somethingto join others and help with an activity If we all pitch in, we’ll have it finished in no time. with Everyone pitched in with efforts to entertain the children.2 to join others and pay part of the money towards something They all pitched in and the money was collected within a few days.3 EAT British English to start to eat hungrily Pitch in – there’s plenty. → pitch→ See Verb table
Examples from the Corpus
pitch with• Walsh, bedecked with new suit and executive glasses, had pitched in with his usual aggressive style.• The Green Party is pitching in with policies on Rubbish recycling and transport.• The maid would go and all of them would pitch in with the housework. 