I found a Defeet sock with an interesting model name and decided to pick some up.

↑This one.
On the distributor's website, part of the model name was censored as F*ｃｋ,
so I ordered it thinking that was just their policy, but


it turns out the censoring wasn't the distributor's decision—that's actually how the original model name is spelled.
Sonya Looney is an MTB racer, but she does all kinds of other adventure sports too.
She's pretty busy with Instagram, podcasts, and cookbooks.
This design is one of the models from Moxy and Grit, a brand she runs (→here),
and since Defeet manufactures it,
it's available through Defeet's distribution channels as well.

Without censoring: "○○ as fuck" is a (pretty crude) slang expression meaning "really ○○" or "super ○○".
For example, "tired as fuck" means you're dead tired,
and "cool as fuck" means it's badass as hell.
In written form it sometimes gets shortened to af or AF.
For instance, if you search the hashtag "#tastyaf" (tasty + af),
you'll find pictures of seriously delicious-looking food.

"Classy" means refined or elegant, so
"classy as fuck" is a crude way of saying "ridiculously classy" or "absurdly refined."