"Inbetweener" is a song by English Britpop band Sleeper, written by the band's vocalist and guitarist Louise Wener. It was the third single to be released from their debut album "Smart" in 1995 (see 1995 in British music). It was their breakthrough single,
Inbetweener wasn't released in english
While it's safe to assume the song would be in english, its hard to know the language of the song or if it has lyrics at all.