I'm going with spit. Different people produce different spit, but I've been blessed with having a very lubricating type. It's free, always handy, and is a great condiment when you're eating or fucking ass (if you're into ass play).
ICE lubricant is a clear natural feeling gel offering an exciting sensation that increases with body heat and feels like ice.Specially formulated water based lubricant designed to greatly enhance arousal and sexual pleasure for both you and your partner.