I hear this song in a lot of episodes but I can't seem to find it anywhere! Please help, I know for sure it's in season 2 episode 13 at 6:05
If I have not been wrong with the scene the song is:
Arararara? (あらららら？) by Yuki Hayashi. It is the twelfth track of the album My Hero Academia Original Soundtrack.
The part that sounds in that scene is from the second 27-29 of the song onwards.