I replaced my septic line today. When I took shower, it brought up some weird water. Then the toilet gurgled,sucked the water down and the lead out through the O ring. What happened?

You have a partial blockage in the main drain line AND a leaking wax ring.

I have a different take on this then Brian. Gurgles indicate a blocked vent and the water being sucked out of the bowl is the suction generated by the system attempting to vent, First things first. Snake the lavatory roof vent. Put out enough snake to reach the base and 16 moor feet. If you have any problems after you snake click on back and we'll address them. Good luck, Tom

" my septic line" which line was that and why did it need to be replaced?