The origin of the wiggles detected in the trajectory of Herbig-Haro (HH) jets, microjets, and radio continuum jets from young stellar objects is investigated. We propose that the orbital motion of a binary stellar system is the cause of these outflow morphologies. The analytical trajectories of a ballistic jet ejected by a source moving along a circular orbit have been derived, and their validity has been checked through a comparison with three-dimensional gasdynamic simulations. We propose a simple method to calculate the mass of the outflow source and the orbital parameters using observational measurements (i.e., the opening angle of the wiggling jet pattern, the separation between successive wiggles, the jet velocity, and the orientation of the outflow with respect to the plane of the sky), and we apply it to the DG Tau microjet, HH 47, and the Serpens radio continuum jet. For these three objects we obtain orbital parameters and masses that are reasonable for pre-main-sequence binaries. From this result we conclude that the observed wiggles (of these three outflows) can indeed be interpreted in terms of a model of an outflow ejected from a source with an orbital motion.