A new smartphone app teaches users how to pleasure women by having them lick their phone's screen.

Lick This puts users through a series of licking exercises like keeping a beach ball bouncing by flicking it upward with the tongue. In another, users can move their tongues in circles on a pencil sharpener.

The problem: smartphones are notorious havens for bacteria and microscopic fecal matter, so licking the screen could make users sick.

However, the developers behind the app recommend putting a piece of plastic wrap over the screen before use.

The app is free.

Read more: Fast Company