A couple of episodes back.
Arya asked Minissha to go and get the kitchen scissors to trim some hair on his head.
Praneet raised this as an item - he had been criticized by everybody when he had used the kitchen scissors for trimming his beard in the first week.
When they confronted Arya, he outright lied that it was used to cut some thread (presumably from his clothes). But he was caught, since Minissha didn't lie and said something like he asked me to get the scissors so that he could cut his hair.
Then Arya started singing - Jab main chhota bachcha thha, badi sharaarat karta thha, par meri chori pakdi jaati... jab roshan hota bajaaj.
(well - that last part I made up about Arya singing that jingle. But the rest of it is pretty much true).