Friends fail to understand a 'double negative' on friendship day

So many of my friends wished me 'happy friendship day' on Whatsapp. And well, I was gonna just type 's2u' and move on with my life, but I chose to be over smart, stupid me. And I did this...

What I really meant -

No sad friend(ship) day

No sad = happy

What my friends thought I meant -

Friend: Happy friendship day dude

Me: No, sad friendship day ):

After this incident I felt stupid that I wrote that. Later, I messaged each and every person "no sad = happy", sometimes chats get really awkward...

Anyways Happy friendship day to all, have fun.

[Edited: 9th Aug 2013]