Hear ye, hear ye, listen to the voice of experience!
If you feel like hurling at anytime during a given day- let's use a Cantata, just for kicks, DO NOT CONTINUE TO SAID EVENT!
If however, you MUST go, should you have to excuse yourself directly before your part for such reasons as, say, that slight rising feeling in your throat making you feel like oh-my-meatballs-I'm-gonna-spew, in said event, do not continue on to said part.
If you have still not got the picture, you should exit quickly out the side door from the church platform at a strategic break in the song in said part. This will prevent you from spewing on the pretty Memorial Poinsettias in the front of the church. I doubt that those commemorating lost loved ones would appreciate such defamation.
After you exit, it is likely that several people will follow you, and then your cousin will take you home.
Anyway....that was my eventful evening. I think the church has the online video of the Cantata up. I am not strategically exiting. This was not planned. I was going to be sick. Oh happy day.