(Mat 13:10) And the disciples came, and said unto him, Why speakest thou unto them in parables?
(Mat 13:11) He answered and said unto them, Because it is given unto you to know the mysteries of the kingdom of heaven, but to them it is not given.
(Mat 13:12) For whosoever hath, to him shall be given, and he shall have more abundance: but whosoever hath not, from him shall be taken away even that he hath.
(Mat 13:13) Therefore speak I to them in parables: because they seeing see not; and hearing they hear not, neither do they understand.
Jesus was asked why he was not speaking in a way people would understand he told them it's not for them to understand.
(Joh 6:52) The Jews therefore strove among themselves, saying, How can this man give us his flesh to eat?
(Joh 6:53) Then Jesus said unto them, Verily, verily, I say unto you, Except ye eat the flesh of the Son of man, and drink his blood, ye have no life in you.
(Joh 6:54) Whoso eateth my flesh, and drinketh my blood, hath eternal life; and I will raise him up at the last day.
(Joh 6:55) For my flesh is meat indeed, and my blood is drink indeed.
(Joh 6:56) He that eateth my flesh, and drinketh my blood, dwelleth in me, and I in him.
Jesus spoke a parable to them that was not to be taken literally but if they knew the scripture should have understood it.
(2Sa 23:14) And David was then in an hold, and the garrison of the Philistines was then in Bethlehem.
(2Sa 23:15) And David longed, and said, Oh that one would give me drink of the water of the well of Bethlehem, which is by the gate!
(2Sa 23:16) And the three mighty men brake through the host of the Philistines, and drew water out of the well of Bethlehem, that was by the gate, and took it, and brought it to David: nevertheless he would not drink thereof, but poured it out unto the LORD.
(2Sa 23:17) And he said, Be it far from me, O LORD, that I should do this: is not this the blood of the men that went in jeopardy of their lives? therefore he would not drink it. These things did these three mighty men.
David was thirsty in battle wished he could have a drink from a well his men risked their lives to fetch him water. When David realized what they did for him he wouldn't drink because the water was their blood because they risked their lives to give to him.
(Joh 4:10) Jesus answered and said unto her, If thou knewest the gift of God, and who it is that saith to thee, Give me to drink; thou wouldest have asked of him, and he would have given thee living water.
(Joh 7:37) In the last day, that great day of the feast, Jesus stood and cried, saying, If any man thirst, let him come unto me, and drink.
(Joh 7:38) He that believeth on me, as the scripture hath said, out of his belly shall flow rivers of living water.
Jesus' teachings are referred to as the waters of life these waters are his blood because he put his life in jeopardy even to the death to give it to us. This is what he meant by drinking his blood and eating his flesh the Blood is the danger he was in the flesh is the death which happened to him to give us waters of life. If we recieve his words which are the waters of life we are drinking his blood and eating his flesh.