JOHNNY-ON-THE-SPOT

(informal) a person who is on hand to perform a service, seize an opportunity, deal with an emergency, etc. —SHSBC Binder 16 Approved Glossary, —5th ACC Vol 2 Glossary (Final Approval 7/12/89), Random House Dictionary Second Edition, —3rd South African unpublished Appr GLS (19.3.92)

(informal) a person who is on hand to perform a service, seize an opportunity, deal with an emergency, etc. (informal) like a person who is on hand to perform a service, seize an opportunity, deal with an emergency, etc.