the act of "sliding under" specifically a desk or table. Most often occurs in during extremely boring lectures or by small children trying to make a sneaky get-away from the dinner table.
The class size dropped considerably as more and more students slundered to take naps.
After perfecting his slundering skills, Drew seemed to get shorter and shorter over the course of the meal, until he disappeared all together.
The verb "to slunder" means to soil, ruin in a dirty way, make grimy or filthy - but in a non-physical way (see examples). It originates from "slander", and the "un" which is changed originated either from a desire to incorporate "under" into the word - or, more likely, to utilise the un sound from cunt - and thus capture some of the foulness of that, the most terrible of words.