I was sixteen when I first heard this word. I was visiting a friend who had moved to England, and one evening in a Chester pub, I overheard a man utter the word after his mate had meticulously described some social initiative the Thatcher government was tabling. I discreetly asked my friend for a definition, to which he replied,
“Bullshit. Nonsense. Rubbish. But the word means balls.”
My friend grinned and nodded.
“What a great word!” I exclaimed.
As I finished my pint, I made a solemn teenage vow that I would incorporate the word bollocks into my active vocabulary from that moment forward; however, like most of the solemn vows I made back then, nothing ever came of it -- not even after I discovered the word featured in the title of a Sex Pistols album.
Etymology Online offers the following on this vulgar British term:
"testicles," 1744, variant of ballocks, from Old English beallucas "testicles," from Proto-Germanic *ball-, from PIE root *bhel- (2) "to blow, swell." In British slang, as an ejaculation, "nonsense!" from 1919.
The word bollocks also led to the more recent verb bollix, coined in an apparent euphemistic respelling in the US in 1937 to describe botching, bungling, ruining, or messing up something.
Though the noun and verb have different spellings, their pronunciation is the same, which could be confusing if one is a bit hazy on the context.
Imagine bollixing bollocks!