Not sure if this works everywhere but this popped up on my local Domino's facebook page. Behind each door is a voucher code for advent.
The 1st door had £10 off £25, not sure what the others will be but worth checking if you're getting some pizza!
My local is Shrewsbury but I'm sure it'll work elsewhere :)
Day 1: £10 off £25 spend
Day 2: Buy one get one free