we do the usual sad irish songs like `` the mountain of mourn , '' some comic ones like `` galway bay , '' and then rip into some fast reels like `` the green groves of erin '' and `` the merry blacksmith , '' with me on the fiddle and mairead on the whistle , and then liam ca n't stand it anymore and decides not to be the grumpy dad and pulls out his concertina and plays a hornpipe and mairead and i link arms and dance to the delight of all .