Baskin Robbins is offering a scoop of ice cream for only $1.31 today, the 31st, and these other 31st throughout the year: August 31st, October 31st, and December 31st.
And on these other 31sts, they're discounting 31% off their sundaes: May 31st and July 31st.
The reason why they're doing this is unclear. Their promotion has logos proclaiming they're celebrating "Number 31", but from what I can tell, it's not some sort of anniversary. Baskin Robbins was founded 70 years ago.
But even if it's nothing more than a clever promotion celebrating nothing in particular, it's admittedly a very good deal. $1.31 a scoop is about 50-cents cheaper than a scoop of Thrifty's ice cream at Rite-Aid, which, by the way, is offered 365 days-a-year for its current price of $1.79–the cheapest price I've ever found for a scoop anywhere.