A superstition among the stoner culture that smoking marijuana with a white lighter (especially a Bic) is bad luck. This superstition persists to the point that many smokers will refuse to smoke until a non-white lighter is found. A possible reason is that many smokers will cover the bowl while inhaling to slow the burn rate or use the end of the lighter to pack the bowl. These both leave telltale burn/ash marks which would be most apparent with a white lighter.
"The white lighter myth is totally true; I would never smoke a bowl with a white lighter"