Sit down in a reclinable armchair and proceed to have sex with your partner.
Right before you finish, suddenly recline the armchair backwards while simoultaniously sitting upright, headbutting your partner as
hard as you can in order to
knock them out. Remove yourself from under them, but keep them laying face down in the armchair. Write the name of your closest bro on their buttcheeks then leave the scene. From that point on, have your bro claim he was the one who did it to your partner.