Two words for you:
It's just plain fun when you can rummage through the store picking out the cutest "pretties" and grinning to yourself because on the outside you might be all Jane Plain in your sweatshirt and sneakers, but you revel in knowing that today you wore the special pink underpants with yellow flowers and green polka dots that you wore the day you saw a double rainbow on the way to work and that the world better watch out because these are your sassy pants!
Guys just don't have this much fun.
Sometimes I feel sorry for them.
On the other hand, I pray I never, ever, in a million years, have to witness the spectacle of man wearing pink underpants with yellow flowers. My counseling budget just isn't large enough for something like that.