Someone who is rich enough to pay for someone else's expenses, either in a large lump sum or over a long time. Can either be permanent (a rich relative or pimp) or temporary (someone spotting a friend).
Peirce gave a $25,000 check to his ex-step-daughter to be his daughter for the day. She referred to him as her Daddy Warbucks when telling Jeff. (From Community S1E18)