Marceline's Closet Trophy
Lie to Marceline
From the left side of the swamp, go down 1 screen, move to the right a bit, then go back up 1 screen to see a cave entrance. In this cave you can walk up to the pool and press to throw an item in. Select Jake to throw in and when Marceline brings you two animals to choose from, pick Mr. Fox instead of Jake for this trophy. Now try again and tell the truth to upgrade him and the Bananarang afterwards.
I have tested this and you are able to lie to Marceline after upgrading Jake in the NA version (PS3 and VITA), but it has been reported that this may be missable for certain players or regions if you do not initially lie first. Just to be safe, pick Mr. Fox when asked the first time regardless.