Presence of mind....

One of my collegues (a nice chap) came to my place to have to do a friendly chat..
he: Hi padma, when is ur last day here..
(I'm quitting this Company)
Me: This friday..
he had recently got a kid..
so i was asking abt his kid..blah blah..i had severe cold and he was like
He: what happened you seem to be having cold,..
me: (showing the dustbin full of tissue papers which i used to blew my nose) ya very severe indeed (smile)
he: oh... that's y i see a lot of paper tissue paper missing in the rest room..
me:(without even thinking) i don't use gents rest room u c..
he: (surprised for a moment and smiled) you have very good presence of mind...
I just smiled...
he went back to his place.
After sometime i was thinking abt this matter.. and was wondering how would he have reacted if i had told" oh.. U use ladies rest room" ;;)..