Question
I have something really slimy in my lawn, we also have alot of moss (green and black). Over the past few years we have noticed a huge increase in this green coloured slime. Besides being really gross to step in with bare feet it is also slippery... my kids and I have slipped a few time when running across the lawn.    How do I get rid of this and what is it?  

Answer
some of the solution depends on where you live...i'm in southern NJ. we have cool weather grasses(fescue, blue grasses, perennial ryes, etc.). sounds like a fungus - normally a sign that the lawn is wet after the sun goes down. if you are doing extra watering towards the evening then that is the problem.
it could also be too much shade. you need to remove the bottom branches(back to the trunk) of any shade trees on the property to allow more lite and air circulation into the areas.
raise the soil pH. lime 2x's per year.
now - and again in the fall(mid to end of sept)... start in the fall by aerating(rent an aerator) the areas. then apply turf lime(40-50 lbs/1000 Sq Ft). and i don't know if or how often you are watering your grass.
get to a local garden center/nursery and quiz them on a solution to your problem in your area.  buy your products from them and they should be more than happy to help you.