That person who you have a tiny crush on that you can't get rid of.
Similar to the remaining toothpaste in the toothpaste tube: you can't push out the remaining toothpaste because there is so little left, just like how you can't stop liking this person because it's such a small crush.
There will always be some toothpaste left in the tube, no matter how hard you try.
"Have you met Alex? He's so funny."
"I know right, he's my toothpaste crush!"