them that they are UN/ID No 3028 Class 8. (Batteries, dry, containing Potassium Hydroxide, solid)
That'll stop 'em dead!
I've found (many years ago, when young and impetuous
) that quoting IATA Regnumbers often helps too - you really don't need to know what the reg is, just make up a number . . . . .
(with apologies to that BCAL hostie on the LGW-EDI run, who didn't want to do a bar run
)