I never heard this song untill today and I loved it immediately

Smile Like You Mean It [Alastor's Offer] | By: PARANOiD DJ

Smile Like You Mean It

Thank You And Goodnight, by Black Gyph0n, featuring the pilot cast of Hazbin Hotel. 

Disclaimer: this is not an original song. The song was made by Black Gryph0n and Baasik (sorry if I spelt that wrong)