are they like underwear thongs or like flip-flops?  I though Americans knew thongs as the shoes or has the underwear definition become mainstream now?  Or was that Australaians?
 
Also - are things (underwear or shoes) especially funny?  Maybe a 60 year old man on the beach wearing them?  dunno.

It is the underwear. Deathspank wears a purple thong that for some reason gives him the power to fight evil...nope, the game doesn't make any sense at all :)

I don't think it's a good idea to think too intelligently about Deathspank.

Thong refers to the underwear in the US