When a male shaves the sides of a females head shortly before busting an astronomical load in her hair. The male then proceeds to manipulate this cum-hair mashup with his nutsack until a mohawk has formed.
Hey Buddy, you won't believe the cumhawk I gave my wife last night. She's been in the shower for an hour now.
"Cumshaw": In the Coast Guard, at least (this may be an incident of perpetual under-funding), the commonest definition of "cumshaw" verb is pretty much identical to your first definition of "scrounge" verb. To cumshaw is to get by irregular means--exchanging favors, calling in debts, cutting corners with procurement--what an individual Coastie, a group, a cutter, or the like should be able to get by regular ones.
The Chief cumshawed a spare prop for the 41-footer.
Used in reference to the comfiness factor of anything upon which one should sit, especially haybales. Unless of course you are allergic to hay, in which case, you miss out on the awesomeness entirely.
When you are getting head from your friend's totally hot relative while he is sleeping not 6 inches away and you nut in his hair and style his hair into a mohawk.
To justify this:
1. your friend must have made a cold bastard comment earlier that night
2. Your friend must have a mohawk as his preferred hair style of choice (adding to the overall comedic value)
3. His cousin/sister/aunt/mom must be totally hot and have a good sense of humor
Earlier in that night Kanye called I.S. a limp wristed pussy, so later that night Kanye's hot cousin gave I.S. head and subsequently a cumhawk. It was totally awesome and Kanye didn't know shit in the morning