You have three options:
1: Cigraph's ArchiSketchy, a routine for taking exploded plans or other views comprised of lines and applying pre-set disrutions to them, creating the sketchy look. You can have overshoot and other wierd qualities.
2: Create a new line type in ArchiCAD that is jiggly. I give my irregular line types names like "palsy" and "electroshock."
3: There's an object that does this, too. "Squiggle Object" It will iimport an ArchiCAD 2D line file and apply a given line type [your own jiggline] and a preset amount of overshoot. I don't know the author and am reluctant to offer it up to just anyone out of respect. Can the author let us know if this is of continued value to them and whether it is okay to redistribute?
Dwight Atkinson