Heeeeeeere's Johnny

First, an announcement: We suddenly find ourselves unexpectedly expecting a fifth child. That’s right, FIFTH. One. Two. Three. Four. Five.
We both like to make it clear to people that this baby is unexpected. It helps to remove the “crazy factor.” Stupid perhaps, but crazy no.
Anyway, after we stopped looking at each other and saying “Doh!” we managed to move on to the next natural topic. Baby names.
Since Jill was a little girl she has had lists of baby names. At any given time she can rattle off her top five boy names and top five girl names. Eric cannot say the same. This disappoints Jill, because she genuinely wants him to be an equal participant in the naming process. Here is an example of how our conversations go:
Jill: So what girl names do you like?
Eric: What are my choices?
Jill: The entire universe of names, real or made up.
Eric: That sounds hard.
Jill: Just string your favorite letters together and tell me what you come up with.
Eric: No, I’d prefer if you just give me three names and I’ll help you narrow it down.
It also bothers Eric that Jill obsesses about the name thing. Eric gets bored of Jill always talking about it. For example:
Jill: Miller is a cool name for a boy.
Eric: Uhhhh, yeah . . .. but switching topics, what do you think of the whole Don Imus thing?
Jill: The name Don sucks. Donovan maybe, but ixnay on the Donald.
Eric: [Eye Roll]
Recently, however, we seem to have hit on a formula. It started when Jill suggested the name “John” for a boy.
Jill: John’s a good name. Solid. Universal.
Eric: Boring.
Jill: But what if we gave him the middle name “Cash.” Then, you know, he would be Johnny Cash.
Eric: Coooooooool!
And that, my friends, is how “Johnny Cash” became our honest-to-God, leading contender for a boy name.
The problem, however, with this new-found naming formula is that Jill is starting to get nervous that Eric will use the formula to suggest other names based on male icons. For example, what if Eric wants to name our daughter "Babe Ruth?" Or if he adds names to the boy list like "Jackie Robinson" and "Bruce Lee?"
Because honestly, Jill is just NOT gonna be too keen on breastfeeding someone named Rocky Balboa.
So what do you think? What should we name baby # 5?