If I just drank a beer and another beer 3 hours ago, can I take an Ibu 600?

I’d say you’re probably still in the body.

Google says the following:

Active substances such as ibuprofen in combination with alcohol have no direct effects on one another. However, both have an effect on the gastrointestinal tract and is metabolized by the liver. By means of the combination, the detoxifying element is exposed to a double load.