Can i play Nunu anywhere

Sure! Probably not well, but if you get put as a midlaner and want to play nunu mid, you can do that. Just don't queue up as a support, pick nunu, then abandon your solo queue adc to go jungle and leave them 1v2.

you wont know unless you try!

No.

Playing nunu at all is ban worthy offense.

Kappa.

support, Jungle, his clear is kind of bad for mid or top, but I have seen it.

Not sure if this is a troll but ill give you a serious response. Nunu is honestly a niche pick to fill certain comps, but ive seen him do decent top lane. He does ok into teemo top from experience. I guess you can play him as support too, but thats kind of controversial right now :)

if it is troll, I recommend Nunu ADC with the following build: Gunblade Wits end Blade of the ruined king Rageblade Tabis Ravenous Hydra for good measure

Nunu is best played in the support role with flash/smite, and you go roam around the map and steal the enemy jungle camps.

You can play him Top and Mid fairly well, but he isn't as reliable as other champions. You can also play him Jungle or Support but you will deal less damage than Janna without the same amount of utility so it's up to you. If you play him top, get RoA and then tanky items like Zz or Sunfire. Just spam Ice Blasts and heal up with Q.