kick-start the dog

1. The act of tucking one's semi-erect penis behind their leg and then kicking that leg rearward in order to stimulate a fuller erection.

2. Tucking ones fully erect penis behind their leg and forcefully hiking that leg rearward in order to smack a woman performing fellatio under the chin.

1. I was taking a shower and sprang a semi so I used some hair conditioner to kick-start the dog.
2. Your ex-girlfriend kept talking while giving the weakest head I've ever received so I kick-started the dog and smacked that bitch in the face.