Incongruous alternatives

Overheard when passing a delivery truck parked outside our offices:

"Have you got a lighter, mate? Or a knife?"

Which set my imagination reeling. In what situation could those two implements be possible alternatives?

I can only hope that the courier was wanting, as I guessed, to remove the polythene wrapping from a palette. If he had a trussed up victim hidden in the van whom he wanted to torture then I failed in my civic duty to render aid.