How come they say english words in Japanese Songs?

Yeah, simply because it "sounds cool," funny how sometimes the grammar makes no sense whatsoever. I wonder if people would notice if a J-Pop artist could sing about chicken eggs in a love song. I suppose it's how English speakers sometimes use French in their vocabulary, though not as often. "Monsieur/Mademoiselle/Madame" Another thing is that Western culture has heavily influenced Japan. They even begin to adopt English phrases to replace the older Japanese ones in everyday speech.

its simply because they want to mix english words with their songs, maybe they find it cool to listen too and its blends well with the ryhme.

It's the same with a lot of languages, where there are quite a lot of English speakers in the country. For instance, Elena Paparizou, the Greek singer, has half English, half Greek lyrics in her song 'The Game Of Love', and it's called the Greenglish mix. This is just so that more people can enjoy the song, I suppose.

Probaly because they are no japanese equivalent to that word.

English is used a lot in japanese songs, just because it sounds cool, plus English is one of the most well known languages through out the world.