“It's very dry.”

Your brother tells jokes without laughing, so you can never tell whether he's joking. You're talking about him with your daughter, and she says, "He has a weird sense of humor." You agree, and you want to describe his sense of humor more specifically. You say:

It's very dry.

a dry sense of humor

If someone has a "dry" sense of humor, it means that they make jokes or say funny things quietly, without directly showing that they're joking. A person with a dry sense of humor usually doesn't smile or change their voice much when they're joking. It's almost like they're hiding the joke so that only smart people and careful listeners will get it. British people are often thought of as having a "dry" sense of humor. Here are some other ways that people can be funny:

• If you have a dirty sense of humor, it means that you tell jokes about sex.
• Absurd humor is when people do things that are ridiculous and don't make sense.
• Slapstick humor is something that you mostly see only on TV, movies, and in plays. This is when someone gets hurt, drops things, falls down, etc. It's also called physical humor.

“I can never tell whether he's joking.”

You have an uncle who has a strange sense of humor.

He tells jokes, but his face always stays serious. You get confused by this. Now you're talking about your uncle's personality with your mother, and you say:

I can never tell whether he's joking.

I can't tell whether (clause)

In this case, "tell" doesn't mean "say". It means "decide" or "figure out". The phrase "I can't tell ___" is used to talk about something you're not sure about:

I can't tell whether it's finished or not. I can't tell whether she's being shy or just doesn't want to talk to me.

The examples above use "whether", but you can also use other question words like "how", "what", "who", and so on:

I couldn't tell what they were saying. For the life of me, I can not tell how he did it.

(someone) is joking

When someone "is joking", it means that they're saying something that's not true, in order to be funny:

A: You're quitting? Are you serious? B: No, I was just joking.

You probably also know that "jokes" are little funny stories or sayings that you tell people. When you're doing this, it's called "telling" a joke:

He always tries to tell jokes, but he usually messes them up.

“He has a weird sense of humor.”

Your uncle laughs at strange things and makes jokes without laughing. You don't understand him. Now you're talking with your mother about him. You say:

He has a weird sense of humor.

a weird (something)

"Weird" means "strange". "Strange" has a wider meaning than "weird". You can call things that are not normal "strange" or "weird". But you can also use "strange" for something that you don't know about, even if it's normal:

There was a strange man on my back porch, so I called the cops.

This means that you didn't know the man. Even if he looked like a normal person, he would still be "a strange man" because you didn't know him and he wasn't supposed to be there. Another example:

If you see a strange package, inform the building staff or the police immediately.

have a sense of humor

Someone's "sense of humor" is their style of joking, and also the way that they react to other people's jokes. You can say that someone:

• has a great sense of humor (They don't mind people joking, and maybe they do funny things themselves.)
• doesn't have a sense of humor (They don't laugh at people's jokes. They're too serious.)
• has a witty sense of humor (They come up with intelligent jokes quickly.)
• has a sick sense of humor (They think that disgusting or harmful things are funny.)