"We eat lunch."
Translation:Wij eten lunch.
nothing, except middageten is used much less than lunch nowadays (middageten is a Dutch word but the imported English word lunch has taken over middageten)
If you place the article before middageten it's correct. "Wij eten het middageten".
Interesting, I guess you're right, so do you have the same weird feeling with ontbijt, lunch and avondeten? I only wouldn't use Wij eten diner all the other ones sound normal to me.
Then I would say "Wij zijn aan het middageten" instead of "wij eten middageten". If someone would say that where I grew up people would say "You are not from around here are you?" :)