How do I clean this thing??

[u/FarAd1643]

I'm a complete noob at cleaning the lids of cups, don't judge me. I recently got this tumblr, and this is the part that covers the hole of the lid. I tried scrubbing it with a sponge, but it doesn't come off all the way. Hell, I even tried using a paper towel. Honestly the only drinks I put in this cup are water, black tea, occasionally chocolate milk, and occasionally soda. Please help!! This stain is annoying me and I don't have any fancy cleaning products made for this.

[u/Beginning_Tea4506]

I've got a toothbrush I use for the fiddly bits?

[u/eamceuen]

Toothpick and/or Q-tip?

[u/Which-Break5673]

I’d let it soak in hot water and dishwashing liquid and then use baking soda/bicarbonate to scrub it