Especially not after they brush their teeth, but if there is nothing else, go for something yummy, but healthy. Tell them that you will read to them only if they are in their pajamas by a certain time. And stick to your guns. Although it will be hard, don't give in to their pleas and complaints. And next time they will be much more likely to get into bed.
Bedtime stories are a favorite.
You can bring along your own books for a fun variety or read their old favorites. Make a point of reading to them only once they are in bed so you don't have to deal with getting them into bed later. If you have children sleeping in several different rooms, gather them into the most difficult child's room with their blankets and have them cosy up on the floor or bed until you are done reading. Tell them that they can only have three call-outs. A call-out is a stall, like asking for a glass of water, or silly questions.