It's a special kind of promise. Nopony breaks a Pinkie Promise. 'Cross My Heart, Hope to Fly, Stick a Cupcake in my Eye!' is the pinkie promise.
Alright man I Pinkie Promise, I Cross My Heart, Hope to Fly, Stick a Cupcake in my Eye, that I will tell you tomorrow.
The most sacred promise anyone can give. When broken, you lose your friend forever. The pinkie promise is done by uttering a chant and doing the motions
AJ: you bettar not tell Twi that ah lost her book. Y'all know what happened last time thayt happened.
RD: Pinkie promise. Cross my heart, hope to fly, stick a cupcake in my eye.
RD crosses a hoof over her heart, opened her wings and gave a flap, and put a hoof to her eye.
AJ: thanks, Dash. Ah really don't know what ah'd do without y'all.
RD: no problem, pal.
RD listened to Twi talk about her new book she lent to AJ. She bit her lip, and opened her mouth to confess. Suddenly, Pinkie sprung out of a potted plant
Pinkie: you'll lose them. Foreeeeeevveeeerrrrr
She slowly disappeared into the plant.
RD: don't question it...
The act of swearing a blood oath while pinkies are interlocked. Breakers of the pinkie promise beware...
Pinkie promise you will call me when you get back!