"Misery x CPR x Reese's Puffs" is a song mashup. It is usually used in animation memes where various characters "sing" the components of the song, with a sad character for Misery, a sexy character for CPR, and a meme character for Reese's Puffs.

Original by misc_mashups on tiktok. Extended version (more common) by Lamaita on Youtube.

Based on Misery x CPR (extended version) by Mizuki and one of the Reese's Puffs rap commercials.

"Misery x CPR" by Mizuki was inspired by "Maroon 5 - Misery (CupcakKe Remix)" by natcakke on YouTube and on TikTok The difference is that Mizuki added vocals from Misery and replaced CupcakKe with a vocoloid.

Misery by Maroon 5 on YouTube.
CPR by CupcakKe on YouTube. (explicit)
Reese's Puffs rap on YouTube.

See also knowyourmeme. Disclaimer: I don't know for sure if any of these are truly the originals; the timestamps line up but it's impossible to be sure..