Money Monday!

Please Help. 

Please Help- I’m curious to know your thoughts on an interesting behavioral finance topic… the gambler’s mentality.  Please comment with your answer to this question:

I recently heard about a shop that held a Black Friday sale where customers would pay full price for their merchandise, but 20% of customers would be chosen randomly after the sale ended to have their full purchase amount refunded.  Given the choice, would you take a guaranteed 20% off or a 1 in 5 chance of 100% off? Why?

Thank You!