Saying nearly everything except orangutan

Marian appears to be able to say nearly everything. When I ask her to say it, she will do so apart from orangutan. I have been asking her to say it for a few months now but to no avail. I don't just ask her out of the blue. There is a magazine that she likes me to go through with her and there is an advert that has an orangutan. I wonder why she cannot say this? There are plenty of other words that are much harder to say and she has been able to say them once I ask her.