I'm going to tease my gf in an online chat that she's rich
Why do you need to tease your girlfriend?
My bone pushing mode is unstable and I want to tease her
Don't do it it's a bad idea, it's rude to talk about your gf's finances in front of others. Respect your girlfriend's privacy and pick another topic.
I just want to make fun of her
You can tease her with other more lighthearted stuff like any inside jokes you both have, as it is not very nice for you to go and say anything about her finances as that is very private and you may end up ruining your relationship over this.