"Tap me out"; to me, would be something like "draw from me/sap from me". You could use the imagery of a plant with some vital fluid, energy, vitality, knowledge, etc.; from wich you could share with someone else. So, you are offering to help someone else by being a source of something vital to her/his life.
"Tap me into you", would be the other way round. The he/she would be source of something pretty much vital to you.
Hope it helps.