Unverified. Go to options and rename your alien one of the following to wear a partcicular hat for two player mode:

ABE ... Top Hat #11
APRIL ... Blond Wig #4
BEHEMOTH ... Red #24
CLETUS ... Hunting Hat #3
DANDY ... Flower Pedal Hat #13
GOODMAN ... Black Curley Hat #7
GRRL ... Flowers #10
PRINCESS ... Tiara #12
SUPERFLY ... Afro #6
TOMFULP ... Brown Messy Hair #2