<p>Leapfrog is a sex position in which the receiving partner is on all fours with her head and torso lower than her hips. The penetrating partner penetrates his/her anus/vagina from behind in a kneeling position. This, as with most positions in which the penetrating partner enters the receiving partner from behind, allows the penetrating partner to ensure that the receiving one, often a woman, reaches a satisfactory orgasm by manually stimulating her clitoris. This position also allows the penetrating partner to control his thrust speed more easily, providing the desired speed and stimulation for the receiving partner. Penetration can be very deep. 

When a woman is penetrated in this position, the penetrating partner may stimulate her clitoris. When a man is being penetrated, the penetrating partner can stimulate his penis or testicles from behind. 

The receiving partner also has the option of rotating her hips against the penis as she is penetrated giving added sensation to both partners. 

This position is also known as "face down ass up", and was the subject of a song of that title by the American rap group 2 Live Crew. 

One disadvantage of this position is it can cause strain</p>