To feel miserable or disappointed after having felt happy, especially because one might have caused the change in his own fortune

You knocked down my mail box, ruined my precious flower beds, almost ran over my dog and you are laughing. Do you think it's funny? Wait until you see the bill for damages, then you'll laugh out of the other side of your mouth

Mi hai demolito la colonnina della cassetta postale, hai rovinato le mie aiuole, hai quasi investito il mio cane e ridi. Lo trovi divertente? Aspetta di vedere la richiesta di danni da pagare e vedrai che passerai dal riso al pianto e non riderai più

He was happy because he gave so little money for that used car, but then he was laughing on the wrong side of his mouth when he realized that the old car was giving him problems day in and day out

Era felice perché aveva pagato pochissimo quella macchina usata, ma poi quando ha visto che la macchina gli dava problemi ogni santo giorno, è passato dal riso al pianto

This term dates from the seventeenth century and was then spelled out by Giovanni Torriano (1666): "The English say, when one has conveniently reveng'd ones self on another, now you can laugh but on one side of your mouth." (The Dictionary of Clichés by Christine Ammer Copyright © 2013)