Pete Wentz -- Ice, Ice Coffee, Baby

Fall Out Boy bassist Pete Wentz really knows how to balance fatherhood ... and a tray of iced coffee drinks.

The 30-year-old Mr. Ashlee Simpson managed to stay poised while holding adorable son Bronx at a Starbucks in L.A. on Tuesday.

Which is no small feat when you're wearing guyliner and skinny jeans.