I'm a Californian, all right.

[aithne]

What lingo do you use?
1. A body of water, smaller than a river, contained within relatively narrow banks?
stream if it's tiny, creek if it's knee-deep

2. What the thing you push around the grocery store?
Shopping cart

3. A metal container to carry a meal in?
lunchbox

4. The thing that you cook bacon and eggs in?
frying pan

5. The piece of furniture that seats three people?
Couch or sofa, but usually couch.

6. The device on the outside of the house that carries rain off the roof?
Gutters

7. The covered area outside a house where people sit in the evening?
porch or screenroom if it's screened in.

8. Carbonated, sweetened, non-alcoholic beverages?
soda

9. A flat, round breakfast food served with syrup?
pancakes

10. A long sandwich designed to be a whole meal in itself?
mmm, sandwich. This one's hard, because it depends on where it comes from. I mostly call them after the stores that they come from--a subway, a quizno's, a Togo's. They're sandwiches in the generic.

11. The piece of clothing worn by men at the beach?
Trunks!

12. Shoes worn for sports?
Tennies in the generic, but I rarely use the generic, instead using "running shoes" or the like.

13. Putting a room in order?
Tidying or decluttering, depends on what I'm doing.

14. A flying insect that glows in the dark?
Firefly

15. The little insect that curls up into a ball?
Sowbug

16. The children's playground equipment where one kid sits on one side and goes up while the other sits on the other side and goes down?
seesaw

17. How do you eat your pizza?
tip first.

18. What's it called when private citizens put up signs and sell their used stuff?
Garage sale or yard sale, depending on if there's a garage involved

19. What's the evening meal?
dinner unless I'm in Minnesota, where it's supper. (I adapt!)

20. An area of trees, greater than an acre?
copse (if less than, oh, ten acres) or a forest if it's really big.

And more from various sources:
21. When they ask for paper or plastic they are talking about?
Grocery bags?

22. Girls' lower-half underwear?
panties or undies

23. Boys' lower-half underwear?
...depends on what kind. It gets called according to what it is, usually. Undies in the generic.

24. The cloth you had when you were little and always slept with, and perhaps sucked your tongue with?
...blanket? I didn't have one.

25. Warm knitted top typically made of wool?
stocking cap or skullcap, depending on what it looks like.