HD step Sister claims she has no gag reflex and I bet her 100 dollars I could make her puke on my dick whenever I visit step mom and step dad's for thanksgiving extreme porn

My step sister is a huge whore and talks non stop about sucking dick. She's 18 and lives with our parents still but constantly sends texts trying to hook up bragging how good she sucks dick. I tell her no repeatedly until she tells me Im scared and probably have a tiny dick so I finally give in. I'm coming to town tomorrow so I text her " OK time to see these skills,, put up or shut up. Ill bet 100 dollars your crying and covered in puke in under ten minutes and we record it." I arrive and she looks adorable and cocky. Dinner starts and she excuses her self to go wait in the broken bathroom.. I wait a few and then leave and sneak in behind her. She had to change clothes before coming back to dinner