This sound effect can be found on The General Series 6000 Sound Effects Library, which was made by Sound Ideas. It begins with a horse-like whinny and ends with a donkey bray, so it is most likely recorded from a mule. Also, sheep can be heard in the background.
Clean, Full Length and Unedited Link to the Sound Effect
- Ed, Edd n' Eddy (Heard once in "A Fistful of Ed".)