Maybe a Bandanna? cool and functional.

A way to lug all your gear, like a backpack cooler. or a backpack with a soft-walled cooler inside

Folding chairs, they are a pain to lug, but you can get them cheap there, and chicks will love you for providing a seat for them. Well they would if someone else does not offer your chair for you.

the radio's would be awesome, due to overloaded cell towers, but are hard to hear over loud music, and the ear bud's are cool, but they give me a headache. Texting is a good option.

Put some money in your sock, pin your keys inside your waistband, ID in your hat

A TOWEL! sunshade, groundcover, sweatremover, hand dryer, basically a better version of a bandanna.