What is y’all?

Why is the word "alive" used here? What does it mean?

In this clip, "the fastest man alive" can be understood as "the fastest man (in the world)" or "the fastest man (in existence)." It is used to emphasize the quality (adjective) of the subject in the sentence. This pattern typically looks like *adjective(-est) + subject + alive* OR *most (adjective) + subject + alive.* Ex: Jeff Bezos is the richest man alive (in existence/in the world). Ex: Angelina Jolie is the most beautiful actress alive (in existence/in the world).

What does "deal" mean here? Does it mean "trade"?

"No big deal" is an idiom that indicates that something is fine and not a problem. Ex: A: I can't drop it off today, can I drop it off tomorrow? B: Sure, it's no big deal.

Does "peak" have a different meaning than "look quickly"?

"peek" means to "look quickly", or "a quick or furtive look". Sometimes it is confused with "peak", which means "the pointed top of a mountain", or "maximum".

What does "tis" mean?

Great question. The word "tis", is a very old contraction of "it is". You will often see it written either as "tis" or "'tis", but with or without the apostrophe it is still the same word. ‘Tis is also known as a proclitic, which is a word that “is closely connected in pronunciation with the following word.” Basically, ’tis was probably so popular because it was easy to say (it really does just roll of the tongue), especially if you needed to express yourself in a hurry. While it is not as popular these days, it can still be used and is not a strange word to hear. Ex: Tis such a shame he missed his game. Ex: Tis too early to go home.

Could you explain me about the expression "pull on someone's leg"?

To "pull someone's leg" means to play a joke on, tease, or fool someone. It is an informal expression that indicates a feeling of surprise or incredulity. Gru has used this expression because he wants to confirm if Otto is being serious or joking around with him. The speaker says "pulling on my legs" but this is actually a mistake. The correct expression is "pull someone's leg." Ex: My boss says he's related to Bruno Mars, but I think he's just pulling my leg. Ex: Don't believe the fortuneteller. He's just pulling your leg.