To be put in the position of sidechick while dating someone who wants to go back to their ex or find a new chick. But they want to see you on the side.
"Grace just got sidechicked because her boyfriend went back to Andrea but keep her on the side."
the other woman; also known as the mistress; a female that is neither a male's wife or girlfriend who has relations with the male while he is in another relationship
Kimmy: Look at Tina and Josh...are they going out?
Sally: No Kimmy! Josh is dating Laura. Tina is just his sidechick.
the process of having one's digital data (e.g. contacts, images, music files) suddenly and irreversibly deleted from a local or remote ("cloud") storage device (e.g. mobile phone, computer, server) without having caused, or contributed to, such action
Girl, I would've called you back last week but I got sidekicked and lost your digits