This is a spintria (plural, spintriae). Some scholars have argued that spintriae were used to pay prostitutes, possibly for use in brothels. Since there were a lot of foreigners coming to the city that did not speak the language and most of the prostitutes were slaves captured from other places the coins made the transactions easy and efficient. One side of these coins showed what the buyer wanted and the other showed the amount of money to be paid for the act. There is no direct ancient evidence, however, to support the theory that spintriae were created as tokens for exchange in place of official coinage.
They may have been gaming tokens. They seem to have been produced for only a short period, mostly in the 1st century AD.
Some people, however, speculate that the spintria were gifts given to legion commanders. First, the series of tokens with busts of Augustus were given. Then, the military men themselves parodied the official gifts with the erotic types.
Some of the coins depicted homosexual acts between men.
It’s difficult to find any on for these for sale, as they seem to be pretty rare. The cheapest one (very worn) was sold for $1,194.56.