For those days you just want to play games or when you don’t want to start something new at the end of a lesson; just write some ideas on post-its, laminate them (everything looks better when laminated) and put them in a box (everything is more fun when the pupils get to pick something out of a box!)
Games include:
Hangman, Mime the action, guess the animal noise, picture dictation, my neighbour’s cat, decribe the word, pictionary, taboo, etc.
Change the games often enough to keep interests, put the kids into teams but change them if it becomes obvious someone is going to look like a total loser.
Or Friday class just flew by.