Dee Dee's Lab was what Dexter's Laboratory briefly became after Dee Dee paid off his debt at the end of Dexter's Debt. The lab was completely repainted pink except for a small section which Dexter used, and it was completely filled with frills, toys and Dee Dee's other girly things. Presumably Dexter managed to restore it after likely repaying Dee Dee as it is seen back to normal in later episodes.
In the episode A Dee Dee Cartoon, Dee Dee is shown to posses her own lab in her room which appears bouncy, pink and full of other girly things that she enjoys, and is run by a male voiced computer. In this lab, she seemingly invents many "confections" such as baked goods, while also playing and saving the world. Like Dexter, she also has a giant robot named the Power Princess Unicorn and uses it to save the world from meteors. In actuality, the laboratory only exists in her imagination.