crapper · noun, adjective1
From crap + -er, although possibly repopularized by barracks employing Thomas Crapper's plumbing fixtures used during the First World War. The occupational surname Crapper derives from a dialectal variant of cropper (“harvester of crops, farmer”).
crapper · noun2
Unknown.
crapper · noun3
Blend of crap (“implying that rap music is inferior”) + rapper.
Etymology from Wiktionary, CC BY-SA 4.0.