"surfer pose" ist die Surfstellung -geduckt mit ausgestreckten Händen.

"sinister" in Zusammenhang mit Haltung würde ich als "drohend" übersetzen.

Suggested translation:

Es [er/sie] zeigt die lästige SoBe-Eidechse in drohender/tückischer Surfer-Positur.

- but I would have liked to see the picture.

HTH

I happen to have a bottle of Sobe in the fridge - the lizards look very peaceful. Seeing the picture would sure be helpful...

I would translate that sentence as follows:
..zeigt Sobes berühmt-berüchtigte Eidechse in aggressiver (or bedrohender) Surferhaltung

(I am not sure why the lizard is infamous, but I'd suggest berühmt-berüchtigt or, on a toned-down note, bekannt. Lästig would certainly be incorrect here.)

I was at the grocery store today and looked at Sobe's surfing lizard (he only appears on one of their products, the Tsunami). He's indeed on a surfboard, kind of a crouched position, arms stretched forward, mouth open (you see his teeth). I would not describe the pose as "sinister", rather as intent, competitive or "angespannt" - it's really a pose of intense surfing. You can tell that he's exerting himself, but by no stretch of the imagination does he look threatening (bedrohlich). I don't know how much liberty you can take with the source text (or if you actually have a picture of the surfing lizard), but I'd suggest not using anything like bedrohlich.
Sobes Eidechse, die auf einer grossen Welle surft
or something like that might work for you.
Anyway, I thought I'd add this for your edification in case you don't have a picture of the lizard.
I do hope it helps.