  We show that a White Dwarf-White Dwarf (WD-WD) binary with semi-major axis
a=1-300 AU, which is orbited by a stellar mass outer perturber with a moderate
pericenter r_{p, out} \sim 3-10 x a, has a few percent chance of experiencing a
head-on collision within ~5 Gyr. Such a perturber is sufficiently distant to
allow the triple system to remain intact for millions of orbits while
efficiently exchanging angular momentum with the WD-WD binary. In ~ 5% of the
initial orientations, the inner orbit efficiently scans the (equal energy)
phase space in the region of zero angular momentum. In these systems, the
binary experiences increasingly closer, stochastic, pericenter approaches r_p ~
a/2N with the increasing number (N) of orbits elapsed. Within N~10^5(a/30AU)
orbits, a collision is likely to occur. This is shown by performing \simten
thousand 3-body integrations and is explained by simple analytic arguments. The
collisions are conservatively restricted to "clean" collisions in which all
passages prior to the collision are greater than 4R_WD=4x10^9cm. In particular,
within the last single orbit, the pericenter changes from r_p>4R_WD to a
collision value of r_p<2R_WD. The effects of tidal deformations and General
Relativistic (GR) corrections are negligible in these scenarios. The WDs
approach each other with a high velocity >3000 km/s and the collision is likely
to detonate the WDs leading to a type Ia SNe. If a significant fraction of WDs
reside in such triples, the rate of such collisions is as high as the SNe Ia
rate, and it is possible that some or all type Ia SNe occur in this way. Such
SNe have a unique gravitational wave signature, which will allow a decisive
identification in the future.
