You must have experienced this, you ask them to do something once, twice, three times and then finally when you yell at them they do it.
My dd has a habit of doing this just recently. I'm not sure it's all deliberate, I know she's dizzy. But it's really bloody annoying!
I just asked her, very clearly, to get changed. 10mins later she's still playing with her brother.
She's now in her room and is staying in there until I feel she can come out.
I'm interested to find out how everyone else deals with this.