This happened again last week, and in the past I have tried methods mentioned on here, except for the neem oil and rubbing alcohol ones, because shelling out $10 for a bottle on the offchance it would work when I would only use it for the one thing wasn't really cutting any ice with my budget.
Neither have I ever gone with peroxide, what with it not being recommended and all that.
Tea tree oil didn't work; it made it smell tea tree-y and bad smell mixed; ew.
Vinegar didn't work, although I had high hopes; it mellowed it a bit, not so funky.
Baking soda and boiling water didn't work, even being soaked for a day.
Someone mentioned leaving it out in the sun, so I washed it out well with hot water and soap and put it outside in full sun ... and, going with tradition, forgot about it. Three days later I remembered it and fetched it back.
It's a MIRACLE. Not only does it have no smell at all, but the sun bleached it back to its original translucent whiteness, as it'd been developing a distinct yellow tinge. It felt all right, not sticky or anything, but I figure if you can put silicone bakeware in the oven a bit of sun won't hurt it, right?