So, I too love durian. One of my favorite parts of traveling to Singapore or Malaysia. (Try the "Mountain Cat" durian from the stand tucked behind the Chinatown hawker market in Singapore, or D24 from most other stands... The Thai variety durian are decidedly less delicious members of the family!)

That said, I cannot think of a worse idea than trying to bring one back in checked luggage. (Particularly if you're on my plane!!!)

1) There's a reason why most durian shipped Int'l are frozen. They actually don't travel very well. The temperature and pressure changes in-flight will very likely cause a ripe durian to crack or split along the segment lines, and so there's a better than average chance you'll end up with a nasty, oxidized, spoiled durian when you get home.

2) Whether or not it splits, that smell is "sticky". It will not only make your luggage a smelly mess, but after ~16 hours in a hold, it will very likely make anybody else's luggage in proximity to yours pretty funky.

3) If it DOES split in-transit, the smell will be astounding... Especially during your connection when the low-pressure, cold-temp luggage undergoes a ~60-degree temperature swing while sitting on a sunny tarmac. The one thing that smells worse than fresh durian is spoiling durian!

4) Yes, it's illegal. Any fresh fruit from the region in pax luggage = No.

Don't be that guy. Enjoy it there, and look forward to your next trip. Buy a frozen one from the local Asian market and live with the disappointment as to how bad they are. See the above, as to why prime durian don't travel well...