fun

[1]	merriment , merriment , playfulness , merrymaking , gaiety , glee , jollity , mirth , cheer , high spirits , delight , frolic , festivity , high jinks , amusement , diversion , sport , enjoyment , recreation , entertainment , pastime , joy , pleasure , (Colloq) (making) whoopee
[2]	tomfoolery , play , sport , horseplay , joking , playfulness , clowning , pranks , sport , jesting , jocularity , nonsense , fooling around/about , (Colloq) skylarking
[3]	in/for fun , jokingly , teasingly , in jest , facetiously , with tongue in cheek , playfully , as a lark , for a joke/gag , not seriously
[4]	Like fun , playfulness , Under no circumstances! , No way! , (Colloq) Like hell! , (US) No way , Jose!
[5]	make fun of , poke fun at , tease , deride , (hold up to) ridicule , scoff at , lampoon , parody , satirize , make sport/game of , taunt , gibe , rag , (Colloq) kid , rib , (Brit) send up