postcard of the month

(mailham delivering postcarp)
i bought a sweet itty bitty little calendar. Beneath the tidy grid of days is a postcard, perforated to be torn away and sent. One per month.
I am totally doing it.
Merry Christmas, everyone, sorry to ruin the surprise.
PS. How does one go about perforating? perhaps it is like a paper cutter only with pointy teeth...