You had seen on tik tok the trend where if your boyfriend copies your snaps, send one of you flexing your bicep so he could send the same. You and Sakusa were currently going back and forth, sending snaps as he mimicked each one, so you did it, you sent one of you flexing your arm and waited for his snap. Once you got it, you opened it to see his bicep flexing, the veins and moles on his arm as you screenshotted it, snapchat letting sakusa know in the chat that you screenshotted a snap