Not to be confused with a snowball, which involves spitting said semen.
Note: snowblow is not osculating your mate after injecting a load of semen into his/her mouth, imbeciles. That would be called a snowball.
There are two possible scenarios:
1. the giver holds the sperm in their mouth and then proceeds to kiss the lucky male as they pass the sperm between their mouths. Reminder - to some this is supposed to be sexually arousing
2. When giving head, you blow really hard with your mouth cusped over the penis so the only direction the air has to go is into the penis. the penis and surrounding area then swell, and the prostate is exposed so an immediate explosive ejaculation without orgasm occurs. Thus the term snow blow, the sperm, or snow as it is referred to here, explodes, or blows, everywhere in a splatter/sawn off shotgun effect.
Jenny and Jack had to go to hospital. Jenny because she had an excessive amount of sperm ejaculated into her eye, jack because he had oxygen bubbles in his blood stream causing him to have aneurisms and a heart attack.
Often used as the incentive to perform the blow job but not always. If the girl/guy wants to blow them that badly the Coke is just the icing on the cake... or the coke on the dick.
Girl 2: "Yeah. He was way to ugly... but the Coke seemed to solve that problem"
Becky: That asshole! Did you get him back?
Jenny: Hell yea bitch, I totally snow blowed his ass!