When a girl is giving a guy a blowjob, the guy puts both of his hands over her ears and pulls her as far onto his cock as possible (this works best with a guy who has a large bush and doesn't manscape). Then she can't hear anything, can't see anything, and essentially cannot speak coherently.
While getting a blow job, blind fold your women, then plug both her ears. While your penis is still in her mouth have her say "water" and listen to the sweet music come out of her mouth, if you can understand her.
This is a complex maneuver involving three separate actions.
1) When a chick is giving you head you pull out and come in her eyes rendering her blind
2) You stick your fingers in her ears rendering her deaf.
3) You put your dick back in her mouth rendering her speechless thus the helen keller
A sexual manuever. You straddle your girl friend while she is giving you a blow job, when you are about to cum you stick your entire ball sac in her mouth, shoot your load in her eyes and then stick your fingers in her ears temporarily leaving her deaf, dumb and blind...hence The Helen Keller.
I was hanging out with my girl friend last night and gave her the "The Helen Keller" she was not pleased Dude...I've got to go get her some eyes drops, she says they're still burning...