(n) - A syndrome where you're fed bullshit and kept in the dark. Derives from the method of cultivating mushrooms: they add a lot of fertiliser and keep them in the dark and damp.
A person can suffer from Mushroom Syndrome in any way; the only circumstances are:
(1) A person doesn't tell you everything about a certain situation concerning you/and or them
and;
(2) They tell lies.
Sarah: So how's your relationship with Andy going?
Bree: OMG! He gave me Mushroom Syndrome! It turns out he was actually gay, which he never told me about.
Sarah: Wow! So what did he bullshit to you about? You know, the other half of the Mushroom Syndrome?
Bree: Oh, he told me he didn't break the blender but it *actually* was him!
Used mostly in anime and manga, the term growing mushrooms refers to when a character has become immensely depressed or saddened. The character is often shown to literally grow mushrooms on their body, signifying that their soul is, for the time being, in a dark and dank place. (Mostly occurs with more dramatic and over the top characters who can't stop crying every 2 seconds 😒)
Senpai: (crying because the girl of his dreams thinks he's dramatic and egocentric)
Girl: "Senpai, quit growing mushrooms around me; the smell is absolutely noxious!"
The use of one's penis as a striking weapon. Preferable method is while it is erect. This will make a nice thud noise upon contact with one's face, forehead, cheek, chin, or nose.