A word that is not commonly used in real life. In fact, the only time it's really been used is in Mario Super Sluggers for the Wii, in a certain point in the challenge mode where Wario encounters Waluigi standing on top of a building near a treasure chest in Wario City. The two start arguing and Wario calls Waluigi a beanpole and then Waluigi proceeds to call him a lardlump.
Judging by Wario's body figure and his love for garlic, lardlump most likely means "a really fat person who eats a lot of junk food".
Mom: Oh dear! Our son has eaten too much junk food and now it's causing him to gain a lot of weight. What will we do?
Dad: We'll have to make that lardlump eat healthy. No more junk food for the rest of the month.