If you're referring to people spamming "desu" with a picture of Suiseiseki from Rozen Maiden, that's not meaningless. The original joke is that the character us

If you're referring to people spamming "desu" with a picture of Suiseiseki from Rozen Maiden, that's not meaningless. The original joke is that the character uses "desu" at the end of her sentences way more than is required by normal Japanese grammar. Other characters have similar verbal ticks, e.g. Kanaria with "de kashira".