Did they do a single where the lyrics included "peep through the bathroom door, see your sister in the raw"? I remember being at primary school - so 9-10 years old, and the kids liking this because it was 'rude'.
Na, that was CCS, Tap Turns On The Water.
My favourite 10cc's are, Wall Street Shuffle, Art For Art Sake & I'm Mandy Fly Me, really good well produced pop. The hits compilation is a great listen.