Yeup. WOLFxDarkSoul13 is an author of a Sans x Reader book (go check it out). So I thought, it's close to Christmas like the previous art work, so.....who writes about Sans and what famous character lives in snowy areas? The Skelebros! So here Oapyrus is taking a picture just as Sans made a pun X3

Sans: Awh SNAP, Paps is taking a photo!
Papyrus: NYEEEEEEEEEEEEEEEHHHHHHHHHHHHHHHHHHH!!!!