El que nada no se ahoga

[JennieNYC]

I just started studying Spanish about a year ago, and I need somebody's help here to help me figure out what it could mean.

I have been going out with a guy from Spain. We met on a dating site.
Then he stopped calling me and I see him on the same dating site all the time.
I asked him a question: "Back to fishing?" (I was upset obviously, and was being sarcastic)
He said: "What?"
I replied: "Nada."
That's what he replied to me: "el que nada no se ahoga"

What would that mean? Word for word it sounds like: "Nothing that doesn't drown." Does he mean that he wants me to leave him alone, so to say - to drown?
Thank you guys so much for any input you could give me.