to be fair, tooting also means to blow one's horn. Which come to think of it, also sounds pretty funny.

More seriously, the American Heritage Dictionary gives the following definition:

     v.
    To sound a horn or whistle in short blasts.
    v.
    To make the sound of a horn or whistle blown in short blasts or a sound resembling it.
    v.
    Slang To snort cocaine.

None of which is to fart. I do wonder if that meaning is a regionalism?