During an orgasm why does it feel like I'm urinating.

You may be confusing it with female ejaculation which is entirely different but possibly feels like urination to some. If you check it out, it may not smell like urine. The first time it happened to me I thought the same thing and was completely embarrassed, then I started asking questions and reading and found out it was quite different.

My experience is that orgasms don't feel at all like urination. Perhaps, your urethra sphincter is having a spasm. That is pleasurable.

:p :D
I agree with tickle I've watched many shows on sex tv and when the G-spot is hit it will indeed feel as if you have just urinated. congrats