Green’s Dictionary of Slang

ballocks! excl.

also bollacks! bollicks! bollix! bollocks! bollocky! bollox!
[ballocks n. (3); ult. ballocks n. (1)]

1. [late 17C+] rubbish! nonsense!

2. [1950s+] an excl. of derision.

3. [1950s+] a general excl. of annoyance, frustration.