"This is a convenient box of treasure left by the pirates!"
"Expecting a box of treasure? Too bad! It's me, Mimi the Mimic!"
*closes box* "Okay, I'll just leave this one alone then." *walks away*
"...hey, are you just gonna walk away?!"
"Yeah, I knew it wouldn't be that easy."
Source was a wallpaper site called walldevil, and later I found a version that was mirror-imaged at a site called zastavki. Not sure how satisfied I am with this avatar so you may see more avatar changes.
The green creature is an alien species found in Metroid Zero Mission and Metroid Other M, and it's called a Baristute. I have no idea why it has a name that rolls off the tongue so well. The courtroom wig, however, is some stock art I found on the internet and added in GIMP, because a barrister might wear it.