Golden tickets are for sending cats to parties only on the weekends.

You can see how many you have by going to the dress-up page (3D button when treating cats) and looking in the top right corner.
The trick is to dress up the cats in one outfit from each theme instead of all the same.
If you are in the dress-up room for cats, you can tell which themes are for the party by the disco ball beside the collection name.

If you still have any questions, feel free to contact us via in-app support chat or email us at support@outloud.games