Omg, many of the logo suggestions are looking… preeetty nsfw to me. m)
Okay, but putting that aside… My favourites are https://github.com/tootsuite/mastodon/issues/962#issuecomment-295442521 (the second, non-genital-looking set in that post) and https://github.com/tootsuite/mastodon/issues/962#issuecomment-296230441 and https://github.com/tootsuite/mastodon/issues/962#issuecomment-296419607 (though it does kind of remind me of evernote).
nsfw
"you made penises! you didn't mean to make penises!" i need an emoji reaction for that sentiment