This has been quite the year for Charlie Day. “It’s Always Sunny in Philadelphia,” which premiered in 2005, remains a viable hit among cable comedies. He co-starred in the hit movie “Horrible Bosses” in the summer and has plenty of other big-screen opportunities coming his way. Yet he remains devoted to “Sunny,” which opened doors for him.

The star/producer/writer is amazed that the raunchy comedy still has places to go.