According to Vivian (YouTube Channel Vivian Tries) Fungalitus is present on items that you think are clean but you're not sure.
I just got these new metal straws at the Dollar Store. They are probably okay to use but I think I'll put them through the dishwasher just in case they have Fungalitus inside that I can't see.
The act of wearing tropical or hawaiian themed shirts/attire often out to bars, parties, or other social occasions. Typically done regardless of the current season or weather, contradicting the traditional context in which it is appropriate to wear such clothing.
Person 1: We should go out tonight, but I don't know what to wear.
Person 2: We could do fungo bungo.
Person 1: But we're in the middle of winter!
Person 2: And?