Was it really "イく"? Typically they don't combine katakana and hiragana like that.
Anyway to be precise, the word for "go" ("行く") is pronounced "iku" and is written in hiragana as "いく"; however "iku" is also the Japanese euphemism for "orgasm", when used that way is typically written in katakana as "イク", and as such is typically translated into English as "cum". You know you've been translating too much JP porn when a girl says she's going and you think she's coming.