Groper Train: Forgive My Tongue (1994)

The elderly Handa, Kawahara in his thirties, and the young Ishii are drinking buddies at a snack bar. When they meet, they don't talk about anything serious, but just kill time with small talk. However, today the topic turned to something rather interesting. The train molestation is usually done with fingers, so can you lick them? YES? NO? The bet began. Thus, the three of them boarded the train for 50,000 yen...