Papa Rizz

During the first Undertale livestream, Jackelus quipped what is know canon to the Undertale universe: Papyrus's nickname of "Papa Rizz." Papa Rizz serves as Jackelus's greatest love, making his way onto a shirt, into his content, as special "Papa Rizz Cams," and, of course, has nestled his way deep into Jackelus's very heart. 

• Short Version: Undertale Names Are Easy
• Video Version (21:23): Playing Undertale for the First Time