Wedged discretely between the classic "dog and bone" (n.) and the more contemporary and colloquial-sounding "dog-sit" (v.), lies the perplexing and innocuous entry for "dog's bollocks." Citing usage from 1949, the OED (see link below) defines dog's bollock as:
dog's bollocks n. (also dog's ballocks) Brit. coarse slang (a) Typogr. a colon followed by a dash, regarded as forming a shape resembling the male sexual organs (see quot. 1949) (rare); (b) (with the) the very best, the acme of excellence; cf. the cat's whiskers at CAT n.1 13l, bee's knee n. (b) at BEE n.1 5b.
This is why I like being a student. It not only presents me with ample time to waste scrounging around the linguistic heap that is the OED (maybe get a little credit for it? maybe a 1 c.r. here, or a little thesis proposal there?), but it also automatically entitles me to a free subscription to the OED online, without which it would be impossible for me to purposefully, nevermind casually, come across this little bit of gold for myself. And by gold I mean "vulgar, 60- year old emoticons."