KIRK: And those are some self-portraits.
LORELAI: Aahh! Kirk, you’re nude!
KIRK: No no, I’m wearing Speedos. They’re kind of flesh coloured.
Speedo is an Australian brand of swimwear, founded in 1914 by Alexander MacRae, and now part of the British Pentland Group; in North America it is manufactured for and marketed by PVH. Due to its success, the name Speedo has become synonymous with racing bathing suits, particularly for men.
(In fact it turns out Kirk was actually naked, but Lorelai and Max agree never to discuss it again).