Good news! The ‘5 second rule’ is officially a real thing Thursday 16th March 2017 | Grace food biscuits 5 second rule scientists Scientists at Aston University have officially claimed that dry foods such as crisps and chocolate are A-Okay to munch on after having being on the floor for up to 30 minutes! No more need to feel embarrassed for chasing that last biscuit rolling away from you down the street anymore.