Well...

[He fidgets a bit, looking a little unsure of himself.]

I don't normally...do this sort of thing, so I'm not sure exactly, but I was hoping you'd be able to provide a bit of a distraction so that she doesn't see me approaching and getting on one knee. I'd like for that part to be just as much of a surprise as the rest of it.

[Don't mind him, he got a little overexcited and called you before he actually had a specific plan in mind other than making you a part of it.]