I too heard this ad the other day and thought he said Cougnut. But the second time I heard it I heard him actually say "Cool Nut". The 106 KMEL website has the following listed:
ON BROADWAY , THE BAY’S HOME FOR TRUE HOP-HOP AND R&B IS BRING YOU THE BAY AREA BOSSES THIS FRIDAY WITH LIVE PERFORMANCES BY B-LEGIT, MESSY MARV, AND COOL NUT! BUT WE’RE ONLY GETTING STARTED, CUZ WE GOT THE OFFICIAL KMEL LADIES NIGHT AFTERPARTY ON SATURDAY! THAT’S RIGHT SWING THROUGH ON BROADWAY AFTER THE LADIES NIGHT CONCERT, CUZ YOU KNOW AFTER THE SHOW IT’S THE AFTERPARTY! FOR MORE INFO CALL 510-663-8189. ON BROADWAY IS LOCATED AT 334 BROADWAY IN JACK LONDON SQUARE.