Back when Pappu first became engaged to Pinki, he spoke to his father, "Pinki assures me she is a virgin. How will I know if she is?"
"It's simple, son" replied Santa. "On your honeymoon night, when you get into bed, if she's clumsy, nervous, makes mistakes and is not sure what to do, then you can be fairly sure she's a virgin. But if she gives you instructions and tells you what to do, you'll know she's a lying slut who's slept around."
After the honeymoon, Santa, "How was it Pappu?'
"Just great, Father" said Pappu. "It was just the way you said... and no doubt about it - she's definitely a virgin."
"Was she nervous, son?" asked Santa.
"She sure was Father" Pappu replied. "In fact she was so nervous and confused that when we jumped into bed, instead of putting the pillow under her head, she was in such a state she jammed it under her arse."