What's the verb for hotboxes? Here's the word you're looking for.
hotbox
To smokemarijuana in a small confined area, such as the inside of a car, until it is full of smoke, thereby purportedly intensifying the drug's effects.
To put out a cigarette just before entering a vehicle, then expel smoke in the vehicle.
“However, last night we scored a twomp of this extremely chronic weed, and we hotboxed Shaun's car...I was GONE. Just out of it. Almost uncomfortably stoned.”
“There is also the option of a full stock assessment which includes hotboxing, dry matter and blackleg tests and requires 40kg of randomly sampled tubers.”