Is this bullying?

No, that’s not specifically bullying, because bullying means using intimidation, threats, force, and/or other aggressive power to abuse, dominate, control, etc.

Since he’s not meaning to be hurtful and is doing it for fun, the intention seems to be to tease. Since you wrote your sister said “lol”, it sounds like she at least doesn’t seem particularly hurt or upset by it, and maybe she even enjoys it and it might not be any kind of problem at all. But it sounds like he might be a bit thoughtless or insensitive about it, and there is of course some point at which teasing can become upsetting or hurtful.

So maybe, in some cases, it could become a problem in a relationship, that could end up turning into bullying.

I would look to see whether the others seem to be just amused, or actually bothered, in the most extreme cases.

It’s a jerky, power play move. My best friend’s boyfriend does stuff like that frequently, and it always bothers me. My friend would be bothered, and mention it, if someone else did it, but she tends to justify his rude behavior by trying to make it seem “less bad” by saying that he was just teasing, even though it’s rude. He, on the other hand gets all bent out of shape if other people make any types of humorous comments about anything (not insulting jokes about people) because he feels usurped, or interrupted. In my opinion, these types of people like to control other people. Belittling them is one of the easiest ways to do that, especially when the insulted person is too hurt or embarrassed to say anything, or doesn’t want to incite the insulter to anger, which tends to happen when these people are called out.

It sounds passive-aggressive to me. And yes, as @Kardamom said, it’s “a jerky, power play move”. He sounds most unpleasant to live with.

It is certainly not bullying in my opinion but your Brother in Law appears pretty childish to me.

He needs to grow up a bit.

Perhaps it would be great to play him at his own game and whenever he opens up a present make the same childish noise and comments as he does and see how he feels.

I would not mind betting he would not like it and if so he should be told that is exactly the same way he acts.

Sounds like he has a superiority complex.

I would find it hard to be subjected to that type of teasing without saying something to the person, like “I really don’t find it funny” or “please stop your teasing.” I would be tempted to make fun of him in turn but the it just continues the teasing behavior and the goal is for it to stop.

When you learn about domestic violence, teasing like this is on the circle of domestic violence.

In the lavender:

http://wingsforjustice.com/domestic-violence-wheel-of-power-and-control/

No, but close. It’s verbal aggression.

It’s not bullying exactly but it is hurtful and for that reason he should stop doing it.

I just saw this in Dear Abby today: ”[R]idicule isn’t humor. In fact, it can be construed as a form of bullying.” Here’s the context:

DEAR ABBY: A bunch of kids on my high school soccer team continually and intentionally mispronounce my name as a joke. I have corrected them on many occasions, but it only made it worse. They think it is hilarious, and my coaches don’t do anything about it. I don’t know what to do.

ANNOYED IN ILLINOIS

DEAR ANNOYED: Try ignoring it. However, if that doesn’t stop them, recognize that ridicule isn’t humor. In fact, it can be construed as a form of bullying. Because you have spoken to the coaches and they refuse to intervene, talk with the school principal about it. And if that doesn’t solve your problem, your parents should have a meeting with the administrator and put a stop to it.

Some people feel awkward with humor. If he is surrounded by ladies, he might feel a desire to be family, but unsure of how to behave.
Try aiming certain expressions to him that will help, like a surprised expression and smiles when he does it well, and a sort of yikes expression when he is failing. If you bring it up, he might feel like backing off completely. I think it would be better to ask your mom if it bothers her. She may be waiting through it for him to be more relaxed.

I think it’s probably a failure of empathy. I sometimes do the same thing and I have to make sure I keep it in check. I used to do it a lot, now not so much.

I may be a little weird, but what helped me fix the problem was to have someone explain to me that the behavior was hurtful, that other people probably experienced it the same way, and answered my questions about how to define the hurtful behavior as precisely as possible. I think people were trying to give me hints for years, but I didn’t pick up on it (probably because it didn’t occur to me to do extra work to be considerate of other people’s feelings!). But I may not be a typical case. I know some people don’t like being confronted like that.

Also, like @Patty_Melt said, maybe there’s a “right time” to bring it up.

It’s really hurtful. I think he should stop it.

@Poseidon Yep, mockery is a pretty juvenile form of teasing.