Shoujo-tachi no Sadism THE ANIMATION

One of the School Clubs invites his mentor teacher in club activities, but his mentor teacher is just being toyed by members of his club and making his mentor teacher to take powerful stimulants. To stop it, he had to take a drug neutralizer stimulants, but the drug neutralizer stimulants was poured into the feet of the club members. The only way, and inevitably, the tutor should lick their feet one by one to get the neutralizer of the stimulant drug.

(Source: Nekopoi, translated)