Industrial accidents sometimes involve hot coal tar stuck to a patient's skin. Coal tar is notoriously challenging to remove once it has cooled and adhered to the skin. The tradition teaching is to apply large quantities of petroleum jelly to the tar, let it sit for at least 60 minutes, and then diligently try to rub away the tar. Repeat as needed.
What if you don't have any petroleum jelly or petroleum-based products?
Trick of the Trade:
Use mayonnaise
Mayonnaise can apparently be used as an alternative, presumably because it is an oil-based product. There are no published reports in the medical literature, but there are more than several anecdotal reports of their effectiveness.
Anyone use this trick?
Thanks to Dr. Sally Graglia (UCSF-SFGH EM resident) for letting me know about this trick.
Reference
Food for Medical Emergencies on Life in the Fast Lane (see comments section)