Assets and Liabilities respectively
On the Right side there is nothing right and on the Left side there is nothing left.
Thanks to Nigel Hinton of AOH Accountants for that one. He's also pointed that:
Some of you may recall the first time you heard this early in your business career and the many companies that it has applied to since and for historians you may like to know that the first time this joke was heard was in Italy shortly after Pacioli invented double entry bookkeeping at the end of the the 15th century.