How to draw "pouring" effect in gdi+?

See the p开发者_如何学编程ic:

I know gradients, but in this pic, the gradient border is irregular, just like pouring water.

I think you're referring to a "gradient" -- there is a LinearGradientBrush class that you can use for this purpose; you can also find an example on MSDN: Creating a Linear Gradient.