I've found that a book of matches is usually sufficient — and available — to solve this problem. If I don't have one in my pocket (which is rare, albeit I am a non-smoker) I can usually walk up to the counter — and get one. The natural wedge shape can be easily modified — thicker or thin, as the case may require. But I agree — there's little more irritating that either sitting at a rocking table, or on a rocking chair.