To receive a blow job in a car at high speed while taking a dump in a bed pan, or the seat if you could care less, and smoking crack simaltaneously.

See also blumpkin, crumpkin, and speed blump
Jaeff- "Dude, my GF just gave me a speed crumpkin on the HW, and now i'm gonna need some oxy clean for my car."

Joe- "Wait what does HW stand for?"

Jaeff- "The highway bro, duh."

Joe- "Oh, ha ha ha, you didn't use the bed pan, again?"
Get the Speed Crumpkin mug.