Lyric discussion by schonenberg 

Cover art for Mouth lyrics by Merril Bainbridge

If anyone here did the hard research (looking it up on wikipedia) you'll see that there was no intentional sexual connotation.

Bainbridge stated that "(Any sexuality on "Mouth" was) not deliberate - it was definitely not a sexual song. It's just honest - about a relationship, how you feel in a relationship. Sometimes you feel you're in control and the next thing, you're insecure - it's the role playing thing. To me, it's not about straight up sexuality. It doesn't bother me if people connect with that, because obviously it's there, but it wasn't something I was aware of"

http://www.westnet.com/consumable/1996/10.25/revbainb.html

@schonenberg But I would add that they sexual connotation probably helped it sell and be popular. And it's hard to say if it's intentional.

But otoh I think it's a difference in symbolism of language used in australia versus the usa.