how to build a guitar effect with farting harmonics?

To create a farting harmonic effect, you'll need a combination of different effects. A possible setup could include:

A low-pass filter: This will cut off higher frequencies, simulating the muffled quality of a fart sound.
An envelope filter or auto-wah: This can help create the dynamic, sweeping sound of a fart.
A pitch-shifting effect: This will create harmonics by shifting the pitch of the original signal.
An optional distortion or fuzz effect: This can add more character and grit to the farting sound.