Nik's intentional romp through Wal-Mart in a disabled cart is both tasteless and hypocritical.
There are people who legitimately grew up poor, were veterans, or grew up in a household with poor eating habits or other dysfunction, and now are fat as a result of their background (and borgers). Nik, who apparently was well off enough to go vegan for a long time, has no such excuse to do this. By pantomiming people who use these carts, he shows that even with his opportunities and background, he was too retarded to avoid that fat, fat, fate; in no respect is this comedic or a parody, which is what he must think it is, putting that corny background music on.