Wow, we just had this thread yesterday. Squid is a rider who rides with less gear than he/she should and well beyond his/her skill level. Flip flops and shorts is common squid apparel. Derived from Squirly Kid (Harley riders called non-Harley riders this when standard bikes starting becoming popular)
Squid is simply justified as someone who wears SHORTS, T-SHIRT, SUNGLASS.
I also classified people as squid when they are in full leather but with no lid. Just a bandana and a sunglass. Just my .02cent
i had the same question back in the day velo, in the navy we all new that we were known as squids, just like marines are known as jarheads. but when i got out and started to ride, i noticed everyone talking about squids. i thought they somehow knew i was in the navy and were talking about me. :lol