Slimy offwhite color discharge from rectum when i push with no bowel movement. sometimes it's brown but this time there was alot and it's off white?

Rectal discharge: Young woman with a white-ish rectal discharge when she strains and there is no B.M. This is mucus, and is normally produced by the colon and rectal lining, and can be increased when there is spasm, IBS and more rarely when there is inflammation or polyps. Without blood it is rarely a source of a serious problem, and a simple sigmoidoscopy or colonoscopy can rule those out.

Situation?: In this case it would be helpful to have some additional detail. For example, have you engaged in anal intercourse? Is there any pain when you go to the toilet? Are you constipated or have you had diarrhea? Any fever? Could the material have been expelled from the vagina while straining? These are a few things that come to mind. When in doubt, a physical exam will help you find answers.