The act of liking somebody's pity like, out of pity for how unoriginal and windy their original pity like was. A sign that pity liking has become overused and should probably be classed as gale force bant.
Facebook user one: 'uninteresting status'
Facebook user two: (after pity liking said status): 'guffaw, i'm so witty and original'
Facebook user three: (after pity like liking the pity like) 'that'll quench that gale force bant'