Deadpool sings mostly whatever ironically fits the occasion. All in all it seems that his taste is pop music both old and new. This can be explained by how much time he spends in front of the TV and in public places where pop music can be heard (Mexican restaurants, taxis etc). Some of the songs he has sung in the comics: Harry Nilsson - Coconut Miley Cyrus - Wrecking Ball The Tokens - The Lion Sleeps Tonight Patsy Cline - Crazy

So what was the first song you loved to sing? The Lion Sleeps Tonight.