Haha that sounds so much like me ^^
Only young people would use these words.
"Mec" and "meuf" are both slang meaning guy & girl. (Btw, how would you say that in American slang ?)
Then "genre" can have several meanings :
1) To say "for example" : "Genre le matin, si j'ai pas pris mon petit déjeuner, faut pas me parler."
2) To express disagreement : "Genre le gars, il me voit, il me dit même pas bonjour !" In this last sentence, "genre" is used as a "Can you believe that !"
3) Used by itself "Genre !" could be a "Wtf !", "Genre ?" could be a "Really ?"
I guess that's why young people use this word so much, one word vocabulary and so many different meanings ^^