- You may also be looking for Harcourt Fenton "Harry" Mudd.
In 2366, Lieutenant Commander Geordi La Forge slipped into an underground cavern while investigating Galorndon Core for possible Romulan incursions into Federation space and landed in a large puddle of mud. (TNG: "The Enemy")
Robert and Jean-Luc Picard were covered with mud during their fight in the Picard family vineyard in La Barre in 2367 and brought the mud into the Picard family home. Marie Picard wasn't amused about this situation. (TNG: "Family")
Sometime in or before 2368, Cadet Wesley Crusher was the unfortunate victim of a prank when Adam Martoni reprogrammed his sonic shower to spray mud. Later, Cadet Crusher got revenge by altering an antimatter regulator to spray chili sauce. (TNG: "The Game")