You just used the bathroom and you left a little something behind that the first flush didn't get. You don't want to waste water by flushing again, so you tear off a couple pieces of toilet paper and drop it on top of the water to hide your contributions. This is called a shader.
Wow, after that lunch I had to leave a shader.
That man's a skater Shader
The opposite of a freshy
Someone whose origins are non-English however their behaviour is whiter than White people
Look at that shader sipping his tea, eating his cucumber sandwiches, smoking his cigar, watching Eastenders