Since i'm from singapore, maybe i can help. To "talk cock" is to talk about meaningless rubbish that is totally irrelevant to the current subject. So if a friend was telling me about his girlfriend's ass while we were actually talking about sports, for example, I'd tell him to shut up and stop "talking cock" meaning "stop talking rubbish". FYI, "cock" is indeed a slang for penis in Singapore. "Talkcocksingsong" is an emphasis on "talking cock", meaning that the person who is doing exactly that is spouting so much useless rubbish to the point that no one even cares.
"Lah", on the other hand is a typical Singlish(singapore english) suffix used to emphasize words, at least that's what i think. In the US, you guys would probably say "No i don't like this" whereas the typical Singaporean reaction would be "No lah, I dun like dis one." The meanings are totally the same but the way they're spoken are not. In this instance, the spoken emphasis is on the "lah" to emphasize the fact that the speaker does not like something.
Singlish may sound weird even though it is basically English bcos it borrows a lot of words from the other main spoken languages in Singapore such as Mandarn and Malay. For example, "suey"(pronounced soo-way) is a Chinese dialect word meaning "unlucky" while "makan" is Malay for "eat" and both are commonly found in Singlish.
Hope I didn't bore you and hope that answered your questions. For more info, visit talkingcock.com; it has a useful Singlish-English dictionary to further help you guys out.
