On December 25, Isaac Newton's birthday, we celebrate the existence of comprehensible physical laws. One way to celebrate Grav-mass is to decorate a tree with apples and other fruits. Glue them or attach them, but not too well! The idea is that occasionally a fruit should fall. Put them on the tree no more than 2 feet up, so that they won't get damaged or hurt anybody when they fall. Another way to celebrate Grav-mass, in a group, is by telling each other about scientific knowledge and understanding, or discussing what kind of experiment could answer an unresolved question about the world.
(I read this, liked it so much! - copied & pasted too - on Richard Stallman official site)