M.C Birthday is a rapper who works in the Ice cream parlour where Ned Flanders is taking the residents from Springfield Retirement Castle out for Jasper's birthday. When The Squeaky-Voiced Teen hears of Jasper's birthday he presses an alarm, prompting M.C Birthday and the Goodtime Gang to perform the following rap:
YO, YO, YO, Give it up for M.C Birthday I said a Birth, a Day, A Birth of the Day Now My good time gang will blow you away
Based on M.C. Birthday's traffic-signal jewelry, he appears to be M.C. Safety, seen earlier as the leader of M.C. Safety and The Caution Crew .