I would recommend putting a condom over it with, of course, lube on the outside of the condom, and lube between the condom and the plug. That way, if anything goes wrong with the outer layer of lube, the inner layer still allows for safe extraction.
BTW, make sure that everything is compatible. That is, don't put oil based lube on a latex condom or silicone lube on a silicone plug, etc.
"Once in a lifetime every man is entitled to fall in love with a gorgeous redhead" And some of us get lucky and marry her.