"Soft nuttin" is something that can happen to any adolescent male. The term coincides with the ejaculation of sperm. A male is said to have "soft-nutted" when his penis is completely flaccid, yet somehow he ejaculates instantly.
Soft nuttin can be triggered from various situations. For example: Seeing something very sexual that makes you blow your load.
Soft nuttin can be very unexpected and unannounced. The element of surprise is what always gets you.
Damn that girl was so fine, I was straight soft nuttin'.
I soft nutted when I saw Keisha bend over.
I'll bet Mr. Cornell soft nutted when his wife told him that she would blow his cock!