It is said in a motivational Poster that if you keep on typing Desu, you will turn Japanese, people believed that, and that's now what you will constantly hear from people who want to prove they're Japanese, also see kawaii for another annoying weaboo term.
Person 2: SHUT UP!
My WOW marriage fell through, it sucks, desu!
Do you like my new cat ears? I just bought them along with a large collection of leather belts, desu!
I am a massive power tool, desu!
2. A huge 4chan meme that sorta went on to other sites. Suiseiseki, a character from the anime/manga Rozen Maiden, are nearly always mentioned. It usually is in motivational posters with Suiseiseki.
2. Cheese, it is awesome, desu!
Unfortunately, the copula has been bastardized and misused too often by people who don't know anything about Japanese. If you want to sound like a complete fucktard, use desu at the end of your sentences while speaking in English, or use it excessively at the end of every sentence, even when the sentence doesn't require it to be used.
僕は心理言語学の大学院生です/だ - Boku wa shinrigengogaku no daigakuinsei desu/da - I am a graduate student in psycholinguistics.
E.g., 2 - Confirmatory sense
この映画は素晴らしいですね？- Kono eiga wa subarashii desu ne? - This movie is great, huh/don't you think?
E.g., 3 - Interrogative sense
Me: 日本語を学んでいる - Nihongo wo manande iru - I am learning Japanese.
ネイティブ日本語話者 (Native Japanese speaker): 本当に？いつから学び始めたんですか？Hontou ni? Itsukara manabi hajimeta n desu ka? - Really? When did you start learning?
Me: えっと、約7ヶ月間前に始めたばかりです/だ ただ初心者です/だ - Etto, yaku nanakagetsu-kan mae ni hajimeta bakari desu/da. Tada shoshinsha desu/da - Well, I just started about 7 months ago. I'm just a beginner.
ネイティブ日本語話者: そうか？じゃ、頑張れ！- Sou ka? Ja, ganbare! - Is that so? Well, do your best!
E.g., 4 Improper use
Stupid person who doesn't actually know or isn't learning Japanese: OMG! Isn't that cat so kawaii desu^_^?
Me: 糞食らえ！英語で話せば、「Kawaii desu」って言うな 愚かな野郎 - Kusokurae! eigo de hanaseba, "kawaii desu" tte iu na. Orokana yarou - Eat shit! If you speak in English, do not say "kawaii desu", you stupid fucktard!
Stupid person: Nani? Speak English!
Me: てめえにそんな事言われたくない！- Temee ni sonna koto iwaretakunai! - Look who's talking, dickhead!
When used by an actual Japanese speaker, it roughly translates to "it is" and is an integral part of Japanese grammar. When used by your average weeaboo, it roughly translates to "I am a stupid American faggot who has no idea what the fuck they're talking about."
"Shut up, you fucking Wapanese faggot."