Goddess Katrina needed to try something she had not done before and that is why she settled on armpit humiliation. It was a lot of fun for her and she had a great time torturing the guy with her stinky armpits. She had not showered but she made sure he licked them clean. He tried to negotiate his way out of it but she did not listen to him at all.
Mistress Ava wanted to find out how gross it was to lick armpits and since she did not want to lick someone else's armpits, she chose to do it to her own armpits. The mistress found out it was gross but she knew it would make for a great way to punish a loser especially if he or she messed with her and she wanted to give him or her a gross punishment.