One of the greatest (in my opinion) athletes of all time Bruce Lee said that muscles like forearms and calves because they are such a dense muscle can be worked everyday and need lots of repititions. I've always herd not to work the same muscle group two days in a row. Is this an exception?

One of the greatest (in my opinion) athletes of all time Bruce Lee said that muscles like forearms and calves because they are such a dense muscle can be worked everyday and need lots of repititions.
The school of thought usually associated with that is that the forearms and calves are used constantly so they have a great work capacity. Therefore, you need a much larger stimulus in order to grow them, which may mean even greater frequency and volume. I don't claim to say that that is necessarily good thinking, but it's the argument that is commonly applied.

I've always herd not to work the same muscle group two days in a row. Is this an exception?
It's an exception to whatever context that statement was made, but it's not an exception to some grand absolute of weight-training. There are very few grand absolutes. As far as training a single muscle group for consecutive sessions, there are good reasons for both doing and not doing so. If you haven't been doing so, as (I assume) a recreational lifter, now may be a good time to experiment.