Snowboard Zippy

In Today’s Zippy, our pinhead reverts to adolescence on a snowboard:

The slang in the body of the strip — airdog, boned out, shred, shred the gnar, pop, nollie, pow-wow — is all genuine snowboarder slang, listed in the enormous collection of snowboarding terms here. The title, “Shagnasty”, is slang, but apparently not slang specific to snowboarding.

I’ll start with the element shag, which is immensely versatile; NOAD2 has five entries for shag, some with distinguishable subentries:

shag¹
noun
1 [usu. as modifier] a carpet or rug with a long, rough pile: wall-to-wall shag carpet.
• [as modifier] (of a pile) long and rough: a shag pile.
• cloth with a velvet nap on one side.
2 a thick, tangled hairstyle or mass of hair: her hair was cut short in a boyish shag | [ as modifier ] : a shag cut.
3 (also shag tobacco )a coarse kind of cut tobacco.
ORIGIN late Old English sceacga ‘rough matted hair,’ of Germanic origin; related to Old Norse skegg ‘beard’ and shaw.

shag²
noun
a western European and Mediterranean cormorant with greenish-black plumage and a long curly crest in the breeding season. [Phalacrocorax aristotelis, family Phalacrocoracidae.]
• chiefly NZ any cormorant.
ORIGIN mid 16th cent.: perhaps a use of shag¹, with reference to the bird’s “shaggy” crest.

shag³
noun
a dance originating in the US in the 1930s and 1940s, characterized by vigorous hopping from one foot to the other.
ORIGIN of obscure derivation; perhaps from obsolete shag ‘waggle.’

shag⁴
verb [with obj.] Baseball chase or catch (fly balls) for practice.
ORIGIN early 20th cent.: of unknown origin.

shag⁵ Brit. vulgar slang
verb [with obj.]
have sexual intercourse with (someone).
noun
an act of sexual intercourse.
• [with adj.] a sexual partner of a specified ability.
ORIGIN late 18th cent.: of unknown origin.

The shag of the Zippy shagnasty (also spelled shag-nasty and shag nasty) is pretty clearly shag⁵ ‘fuck’ (as noun or verb, or possibly adjective used adverbially), but with a shift in sense to something like ‘extreme(ly), very’ (similar to one use of fucking), giving an enhanced variant of nasty. It’s in Spears’s American Slang and Colloquial Expressions (4th ed.) in this sense, with the cite I want out of this shag-nasty mess. Also in Urban Dictionary in this sense:

Unpleasant, grimy, unhygeinic, generally undesirable. [paraphrasable as ‘beyond nasty’] You spunk swallowing shagnasty fuckpig. (titwanker 4/10/03)

Usually used as a proper noun (someone’s name) to show disdain, contempt. Also used in jest on acquaintances. You shut yer fuckin’ trap, Shagnasty! (Ant 8/8/03)

But UD also has a reversed sense:

Freakin’ awesome. Anything that is deserving of a title stronger than ‘cool’ and in a positive sense. “That new shirt is shagnasty, bro” (Tmoney 2/16/05)

Reversals of this sort, converting a slang term of negative evaluation to one of positive evaluation, are quite common. And that’s probably what’s going on in the Zippy title. And possibly in this company name:

Shag Nasty Swimwear Manufacturer, Las Vegas NV: Shag Nasty manufactures the stylish swimwear and fitness clothing you design. If you’re a swimwear designer in need of a high quality and affordable manufacturer, Shag Nasty is the company for you. (link)

Digression on (mostly) irrelevant occurrences of shagnasty. First, there’s Shagnasty Isand:

Shagnasty Island is a small, rocky ice-free island lying 0.3 miles (0.5 km) west of Lenton Point in the north part of Clowes Bay, close off the south coast of Signy Island in the South Orkney Islands.

… The name … arose from the unpleasant state of the island due to its occupation by a large colony of blue-eyed shags (Phalicrocorax atriceps). [The blue-eyed shag is a type of cormorant: shag².] (link)

Next, there’s a family name Shagnasty:

Thank you for your interest in All Natural Shagnasty Raw Honey. Oliver Shagnasty, “The Cosmic Bee Keeper,” has been harvesting honey on Kauai since 1975. (link)

And possibly in this name of a bar and grill:

Shagnasty’s Food & Spirits, Deer Park WA, B.T. Shagnasty, Proprietor [though it's not clear whether this is serious; in any case, the place is now First Street Bar and Grill]

And there are occurrences that seem to evoke shag ‘fuck’ directly, as in the name of an X-rated British tv show, Shagnasty and Muttley, with main characters Randy Shagnasty (“Shag”) and Stan Muttley (“Mutt”).

Finally, there are band names:

Shagnasty: high energy rock & roll (link)

Shag Nasty UK – 1976-79 UK Punk Music (link)

These could be either flaunting nastiness or proclaiming awesomeness. My guess is that the first proclaims awesomeness, the second flaunts nastiness.