Hot-knifing is just another way people have figured out how to smoke their drugs. In this case, the tip of one or two butter knives may be heated red-hot, and when hot enough a favorite controlled substance is applied by sticking it on; and then if needed the drug is squashed inbetween the heated end of a second knife. Watch the smoke form from the mass being incinerated, but if the temptation is too much to resist the ways of inhaling are many; straws, empty pen tubes, bongs without the bowl, bottles with the bottoms strategically removed, or nothing. Be ready, an overwhelming amount of smoke is produced immediately. As far as the heating goes a blow torch is about the best, a stove works well, and a candle will get the job done eventually.
A fair warning though, this will make the knife brittle and ruin the finish, and it can also cause one nasty burn.