When you are so disgusted by unexpected 'shart' that you unexpectedly barf.
Girl 1: I ate so much last night that I actually sharted myself
Girl 2: That happened to me yesterday but I took it a step further. I was having dinner with my grandparents and I was so disgusted that I actually puked.
Girl 1: OMG thats so disgusting, I'm going to barfshart now too!