I don't know what チェキ☆ is supposed to mean, but I put an empty translation note so whoever does know can edit it in without waiting for the GIF to load and/or cycle to a frame where it is visible.
FWIW, EDICT says:
チェキ (n) small instant camera チェキる (v5r) to take a picture with a "cheki" camera
As I remember, it's just a catchphrase Yotsuba says all the time. I've always seen it taken to be the English "check" or sometimes "checky", so I went with the former.
