Yes, a picture is worth a thousand words. However, from the samples I have seen (backgrounds, portraits...) this word is still mysterious to me. Any suggestions? Samples are welcome too!

we are going to add some grunge for my homework today. Stick around.....

Michel,

From http://www.thefreedictionary.com/grungy GRUNGY -

adj. grun•gi•er, grun•gi•est Slang
In a dirty, rundown, or inferior condition: grungy old jeans.

In other words beat up, distressed, worn out (in this case jeans) that you wore as a kid and your parents hated.