when C-H bonds are in conjugation to pi bond, this conjugation is known as hyperconjugation. in this process the bond between C and H gets into resonance by moving of electron pair into the molecue leaving H+ and forms a 'no bond resonance'.reverse hyperconjugation will be in the same fashion as this is in reverse hyper conjugation C-X bond will be in conjugation to pi bond where X is a halogen.in the reverse hyper conjugation the same occurs but with the electron pair moving out of the molecule onto the X atom leaving X-. this also forms a no bond resonance
please have mercy on me if i were wrong and correct me