Was that

Hi! Can you please tell me what this means and where the expression comes from? Thank you - Sax

If you're learning to swim, you start at the shallow end of the pool. If you think you can swim without lessons, you jump in at the deep end.

"Deep Thought" the computer in "Hitchhikers' Guide" or "Deep Throat" ?

(which incidentally I have not seen - apparently there are some really dodgy hairstyles...)