The Java Lava Coffee House is a coffeehouse owned/run by the Finster family.
Chuckie and Kimi work there part-time, and Betty helps Chas and Kira run the place. Chuckie, Kimi and their friends, including Angelica and Susie, hang out there a lot in the spin-off series to Rugrats, All Grown Up!, when they're in middle school.
The coffeehouse is shown to be a very popular hang-out for other kids from their school.