Not just the idiomatic sport wood, not just the idiom with a meta-modifier (huge ironic) added to the head noun wood, but also the figurative use of the idiom to mean not ‘display an erection’ but ‘become extremely excited’, not in a sexual sense.
(On morning wood, see my January piece here.)
Sport wood combines two specialized uses, of sport and of wood. OED3 (Sept. 2008) has this sense of sport:
To display or exhibit publicly, esp. in an ostentatious way
(with cites in idiomatic phrases, but not sport wood or other sportings of erections). And OED2 (draft additions 2006) has this use of wood:
slang (orig. Brit.). The penis; (now usually) an erection (chiefly in to get wood ).
(with cites starting in 1985). Green’s Dictionary of Slang has wood ‘erection’ from 1593, but then things pick up in phrasal cites from 1990-2000:
buff the wood ‘masturbate’
catch wood ‘get an erection’ thus figuratively ‘to become extremely excited’ (Pelecanos quote 1993: “the two-tone model that made Spics catch wood”)
get wood, have (good wood) ‘achieve an erection’
give wood ‘render erect’
pull one’s wood
put the wood to
sport one’s wood ‘display an erection’ – cf. sport a woodie
Then add to this meta-modifiers, as with proverbial in cook someone’s proverbial goose, and you get sporting huge ironic wood ‘(ironically) be hugely excited / enthusiastic about’. Piece of cartoonish cake.