Translation:My sister is trying to eat two trivets.
What I find funny about 'trivet' is that nobody has heard the word before, but we all recognise the object. So what do we call them? I can't think of a specific word (except trivet, which is new to me), but I must have been referring to them by something all this time. Do we just say, 'can you pass me that thing to put under the pot'?
I'd never heard the word either and I'm a native speaker. I believe I have one however, just didn't know it had a name. Here are a couple of pictures for anyone who doesn't know what one is (which is evidently practically everybody:) http://www.leroymerlin.es/img/r25/51/5106/510606/12047952/12047952_z1.jpg Ours look more like this, but are better kept: http://www.laurelleaffarm.com/item-photos/antique-rusty-iron-trivets-primitive-vintage-round-trivet-collection-Laurel-Leaf-Farm-item-no-u62337t.jpg
A coaster is normally something smaller and thinner ehich eould be out under a cup, mug or glass and could be for preventing water rings in a wooden surface, so could be made out of paper, cork etc. A trivet is usually larger and thicker and is for hot objects, so could be made out of wood, cork, tiles etc
A place mat, frequently made of cotton or other fabric, is put on the table under the plate and cutlery.
A coaster, made of leather, cork or else, is placed under a glass or bottle.
A trivet is an iron tripod set up for cooking - usually outdoors.
None of the above is edible.
If they gave us a sentence such as 'put the hot saucepan on the trivet' that could help us guess the meaning of 'trivet' (as most of us clearly don't know the word).
I have a silicone mat to protect the worktop from hot pans etc. If I were going to call it anything, I wouldn't call it a trivet or a coaster, but I would call it a saucepan mat, or possibly a heat mat as someone else in this thread suggests. Or better still, I might call it Steve.