The head rest sex position is an oral sex position most commonly used to facilitate fellatio. In this position, the receiving partner should lie on their side with their top leg lifted up and moved slightly back so his ankle is slightly behind their bottom leg. The partner performing the oral sex can then lie facing the receiving partner, resting their head on the receiving partner's bottom leg.
Partners pictured using the Satisfyer Curvy 3+.
As this position leaves the receiving partner's hands free, it is an easy position to include sex toys into. For example, in the position below, the receiving partner is using the Satisfyer Curvy 3+ to stimulate the performing partner's clitoris. Including sex toys means both partners are receive stimulation instead of just one!