Hey Aquila! I finally figured it out!
After reading your post more thoroughly, I now realize the Baptism Christ spoke of!
Matt 20:22 But Jesus answered and said, Ye know not what ye ask. Are ye able to drink of the cup that I shall drink of, and to be baptized with the baptism that I am baptized with? They say unto him, We are able.
Matt 20:23 And he saith unto them, Ye shall drink indeed of my cup, and be baptized with the baptism that I am baptized with: but to sit on my right hand, and on my left, is not mine to give, but it shall be given to them for whom it is prepared of my Father.
Luke 12:50 But I have a baptism to be baptized with; and how am I straitened till it be accomplished! (The following day Christ was crucified)
He was actually saying "But I have a baptism to be baptized with; and how am I straightened till it be accomplished being dunked in some water".
and
"Ye know not what ye ask. Are ye able to get dunked in some water, the baptism that I am baptized with? It's really difficult, do you think you're capable of getting dunked in some water and have an emotional experience?!"