This is a challenge requiring skill and perseverance. Best not practiced in front of a mirror as hysterical laughter may result in injury. (No responsibility taken for anyone trying this challenge.)
Place a whole gingernut in your mouth. The aim is to flip the biscuit completely upside down using only tongue, teeth and facial muscles. Not for the faint-hearted!
A Krispie biscuit provides perhaps an even tougher challenge with its serrated edges and tendency to crumble in the mouth over time.
Although I haven't achieved this feat personally, both my husband and 16 year old daughter have.
No video has been supplied with this entry for obvious reasons!