Nap

You decide that a nice nap would do you wonders. You fall asleep and start having weird dreams about being chased by a vacuum cleaner. It catches you with its hose by sucking up your dick. As much as you try to get away it just keeps on sucking until you cum.

It is just a dream, but in the real world you body responds and you ejaculate into your tighty whities. You don't even realize you just had a wet dream and you keep on snoozing away.

Not too long after, your breathing starts to slow until it eventually stops. You never awaken.