The first rule of Highlander safety is never return to a Highlander that fails explode. The standard method of safe disposal is to encase in mud strengthened with fibres of Scrotpubium 90 and then bake for 20 minutes at Gas mark 4 until golden brown. As for what you should do. I suggest you make some toast, cut it into soldiers and then boil your head for 3 minutes and dip the toast in it. yummy!
Pour 3 fifths of Scotch down his gullet. Liberally sprinkle some Peruvian marching powder around his nose. Say in a loud voice "Aye lassie, therrre havin a sale on patched condoms down at McFarland's." The Highlander will either explode or ask directions for McFarland's.