Tesco has an offer on beach towels at the moment with £12 for any two towels. However, if you put two towels in your basket head to the checkout, it takes £4 off, giving you both for £4. I've just tried it on two Hello Kitty towels and it's worked for me. It's definitely also working on the 1 Direction towels and St George's Cross.
Not much to say here - there are a few different towels in the offer, and even if you don't put one of the £4 towels in your basket, it takes £4 off at the checkout.
I expect these will all be out of stock in no time though!
Thanks to fluffykitty79 and lisasolo1 at HUKD