SignificanceShear thickening is a ubiquitous rheological phenomenon whereby dense suspensions of particles in a fluid exhibit a viscosity increase at high shear, which can turn into a viscosity divergence [discontinuous shear thickening (DST)]. Although macroscopically well characterized, the microscopic origin of DST is still debated, especially in connection to particle surface properties, e.g., roughness and friction. We elucidate here the mechanisms underpinning DST by carrying out nanotribological measurements of the interparticle contacts of model rough colloids. We demonstrate that rough particles exhibit DST over a broader range of shear rates and for volume fractions much lower than for smooth colloids, due to interlocking of surface asperities, showing that taking an engineering-tribology approach is a powerful way to tune DST.