Not 3D but at least a starting point:
http://media.photobucket.com/image/banana%20suit%20man%20birthday%20cake/tor_andherstupidmouth/Jackson/invgo8.jpg
HTH
Use round cakes stake them up and cut out what it would look like a banana then use fondant to make the hands and feet and the face. but im not to sure how it would look but its worth a try. If you could try to make the hands and feet and the face with cake but use rods to hold it up. If i can find an easier way i'll tell you asap.
Most banana suits are really just long shirts pulled down over normal clothes with most of the clothes still showing. Personally, I think making most of it banana is more interesting - like these.
http://i98.photobucket.com/albums/l241/driger369/AQWiki%20stuff/Malebananasuit.png
http://www.upixa.com/stock-photo-image-search.php?record_id=00025999&activity=detail_view&search_criteria=people
http://fc09.deviantart.com/fs30/i/2008/148/0/c/sasuke_in_banana_suit_by_MIA_1414.jpg
Try molding a fondant banana around the end of a dowel.
Scoop out a half ball space for the face hole and install a head ball there; scoop smaller half balls out of the banana to insert arms and legs (molded onto toothpicks.)
Push uncovered part of dowel into cake, voila - standing man in a banana suit.
Thanks guys. 7yrrt, thus cake needs to be a couple of feet high and I'm not sure the directions you gave me were for something that big. If they were, can you give more details? Thanks everyone! I'm thimkimg I'll just stack round cakes and then "glue on legs and arms made of rice kris pie treats...
Oh, you want the entire cake to be the banana man!
I was thinking of a topper.
Let me do a search for you. There was a tutorial for a ghost cake, using a pointed ice cream cone at the top.
That would work for your banana, if I can locate it
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