Why is my bf’s ass red and swallown?

Patient: Q about SEX (why is my bf’s as s red ..?my bf and i and a friend were playing sex dares so my friend dared me to put a dildo in my bf’s as s so i did (it was fun) .then i dared my bf to put lube in his as s (cuz he has a tight as s) and put two oranges in it i once tried it and they fit .so when our friend left i noticed that my bf’s as s is swallowen and red he said that he liked what we did (i know its wierd) and he said his as s burnsso my Q is why is his ass red and is it dangeros or harmful and what is it ?????