A little tip from Harper:
Don't know what something is, but embarrassed by your lacking vocabulary? Here is a plan that will ensure you remain clever and cute in the eyes of your parents.
1) Point to object(s) in question.
2) Look lovingly at the nearest adult and ask, "Wha is dat?"
3) Wait for the answer with a thoughtful look on your face.
4) When the adult answers, enthusiastically say, "Yes, dat's right!"
Nodding your head helps sell that last part; a little pat on the adult's arm doesn't hurt either.
It's a win-win. You now have a word to put with the previously unknown object and any adults around you will beam at your brilliance.