Kore, kite-mitara. Zettai niau yo. (Here, try this on. It'll totally suit you.)

Situation 1: Mr. Sere and his girlfriend Yuri are out shopping.

ゆり： ねえ、これ、着てみたら。絶対似合うよ。

セレ： え、そうかな。でも、ゆりがそう言うなら、着てみるよ。

Yuri: Nee, kore, kite-mitara. Zettai niau yo.

Sere: E, sō kana. Demo, Yuri ga sō iu nara, kite-miru yo.

Yuri: Hey, here, try this on. It'll totally suit you.

Sere: Hmm, I wonder. But, if you say so, I'll try it on.

絶対 (ぜったい) is an adverb and a noun that is often heard in spoken Japanese to stress something. 絶対 as a noun means "absoluteness," and shows that something is complete and definite:

うちの会社(かいしゃ)では社長(しゃちょう)の命令(めいれい)は絶対なんです。 (At our company, our president's order is final.)

イスラム教(きょう)ではアラーが唯一(ゆいいつ)絶対の神(かみ)である。 (Allah is the one and only god for Muslims.)

絶対/絶対に as an adverb exaggerates the speaker's intention or judgement and is used when they are confident in what they're saying:

今度(こんど)の新製品(しんせいひん)は絶対売(う)れるよ。 (I'm absolutely certain that this new product will sell well.)

エジプトに行(い)ったら、絶対にピラミッドを見(み)たい。

(If I go to Egypt, I definitely want to see the pyramids.)

この仕事(しごと)は絶対に成功(せいこう)させなければならない。 (We must succeed at this job.)

Situation 2: Mrs. Okubo and her daughter Mariko cross at a railway crossing near their home.

まり子： あ、踏切が閉まっちゃう。早く渡ろうよ！

母： だめだめ！踏切が閉まったら、絶対に中に入っちゃだめよ。

Mariko: A, fumikiri ga shimatchau. Hayaku watarō yo!

Haha: Dame dame! Fumikiri ga shimattara, zettai ni naka ni haitcha dame yo.

Mariko: Ah, the crossing barriers are just about to close. Let's cross fast!

Mother: No no! When the barriers start to close, you shouldn't go inside by any means.

絶対 in a negative sentence translates as "never" or "by no means." It illustrates a strong denial:

私(わたし)はアレルギーがあるので、そばは絶対に食(た)べない。 (I have an allergy so I can't eat buckwheat noodles at all.)

あんな強(つよ)いチームには絶対に勝(か)てないよ。

(They'll never win against such a strong team.)

Bonus Dialogue: Ms. Gray and Ms. Oda are chatting.

グレイ： あしたから、旅行(りょこう)だって？

小田(おだ): うん。友(とも)だちと台湾(たいわん)に行くんだ。 実(じつ)は海外旅行(かいがいりょこう)は初(はじ)めてで、ちょっと緊張(きんちょう)しているの。

グレイ： だいじょうぶ。台湾は安全(あんぜん)だし、交通面(こうつうめん)もわかりやすいし、食べ物(たべもの)もおいしいし、絶対に楽(たの)しめるよ。

小田： そうだといいけど。

グレイ： どこに行く予定(よてい)？

小田： 特(とく)に決(き)めていないけど、故宮博物院(こきゅうはくぶついん)は絶対に行かなきゃ。あと、小籠包(しょうろんぽう)を食べたいと思(おも)っているんだ。

グレイ： ああ、いいね。私も大好(だいす)き。

小田： それから、中国茶(ちゅうごくちゃ)も買(か)いたいと思っているの。あとは足(あし)つぼマッサージも絶対にね。

グレイ： いいなあ。楽しんできてね。でも、パスポートとチケットは絶対に忘(わす)れないように。

小田： それぐらいは、わかっている。いくら海外旅行の初心者(しょしんしゃ)でも。

Gray: I heard you're going on a trip from tomorrow.

Oda: Yeah. I'm going to Taiwan with my friends. Actually, it's my first time traveling abroad and I'm a little nervous.

Gray: It's OK. Taiwan is safe, the traffic is easy to understand, the food is delicious and you're definitely going to enjoy yourself.

Oda: I hope so.

Gray: Where are you planning to go?

Oda: I have no particular plans, but I definitely have to go to the National Palace Museum. Also, I hope to eat some soup dumplings.

Gray: Ohh, nice. I love those, too.

Oda: And then, I hope to buy some Chinese tea. I also want to go get a foot massage

Gray: Wow, nice. Have fun! But, make sure you don't forget your passport and ticket.

Oda: I know that much. No matter how much of a newbie to overseas travel I am.