Alyssa T.: Say something - a great big world & Christina Auguilera Heres my #popup challenge entry, so please feel free to #collab on this post so that we can both enter! Because the theme is #duet Simply collab on the post and put "#popup" in the caption. Happy collabing and good luck to everyone!! 😄😄 #saysomething#joinmycollab#popupchallenge#agreatbigworld#christinaauguilera#acapella#acapellaappstore#harmonies