Clients' birthdays

I would like to offer something for clients on there birthday. I do most of my advertising through fb and I advertise in all the groups but I am trying to divert people to my group which they can request to be added to easily.

I would like to offer an add on to an existing treatment but what? I am a bit stumped for ideas.... I would love to offer massage in some way as its my passion but struggling with what to do...

Any advice would be greatly appreciated ) thanks my lovelies

Sent...

Clients' birthdays