All of it...even genres I don't understand (ok...say it now - weirdo).
So...my top ten summertime songs (now this won't be as much fun if you don't play, too).
In no particular order:
In The Summertime by Mungo Jerry
Hot Fun In the Summertime by Sly and the Family Stone
Surfin' USA by the Beach Boys
Summer of '69 by Bryan Adams
Summertime by Kenny Chesney
Boogie Shoes by KC and the Sunshine Band
No Shoes, No Shirt, No Problem by Kenny Chesney
Soak Up the Sun by Cheryl Crow
Amarillo by Morning by George Strait
Sugar Shack by Jimmy Gilmer and the Fireballs
(Summer Lovin...was just too obvious...by I love GREASE!)