That's a new one on me, but it seems to already be well known to aficionados of variations on the Nigerian Scam. A quick google on the phrase "HUMANA PROMO LOTTERY" turned up lots of hits, and [snort!] they all have the same reference number.

Here's how I'd respond:

"Wow! Peter, that's fantastic! Listen, you don't need my account number to transfer funds. I'll make you a deal you'd be crazy to turn down: You hereby have my permission to deduct US$50,000 for yourself (yes, that's US$ FIFTY-THOUSAND!) to use to buy yourself a plane ticket to fly over here and deliver the cashier's check for the balance. YOU GET TO KEEP WHATEVER'S LEFT FOR YOURSELF! Hey, don't thank me, that's just the generous kinda guy I am. It's the least I can do to repay you!"