My sister has been wanting me to get her a pet pig but I don't really want to get her one.
Why wouldn't you want to get your sister a pet pig?
I don't want the smell of pig in the house.
It's understandable if you feel that your sister may not fully be prepared to care for a pig. You should speak up if you think someone may not have the proper tools to care for a pet. Talk to your sister about the responsibilities of a pet and all that is involved.
My problem is that my family is against me. Pig lover appreciation needs to stop here.
It is understandable that it's tough to relay your message considering that your family really loves pigs. But you should speak up if your sister is unable to take care of the pig, because it will make a mess of the house.