passing fan 

Someone who likes something, but not enough to be considered a full on fan of it.

"Oh hey, do you like BTS?"
"Eh, they're okay, I'm more of a passing fan than anything else."

passing fan by unibard August 1, 2020

passing fancy 

a novelty that captures the attention of the general public for a relatively brief period, until either people lose interest in it, or the next "big thing" comes along.

also, an infatuation or a temporary but intense emotional attachment toward an individual.

Just as the hoola hoop of the late 1950s, so too did the Rubiks Cube prove to be a passing fancy after it was introduced in the early 1980s.

I suppose Sue's brief relationship with Tim was just a passing fancy for her, as she's since returned to her husband.

passing fancy by Polo June 10, 2007

Pissing Fanta 

The colour of your urine the day after being kicked in your kidneys.

I got beat down last night, and now I'm pissing fanta!

Pissing Fanta by Nemo Carlisle May 17, 2007