Humping - a very common misconception of this behaviour is that its a Dominance thing - well with bulldogs it's quite often a "I don't know what else to do with myself" behaviour. It's usually a stress behaviour and many bulldogs that have recently been rehomed will hump their new family - sometimes homing in on just one member of the new family. "Aw he loves me" - ummmmmmmmmmmmmm
It almost always calms down after a few days as the dog settles and his stress settles also. However, in the few cases where it doesn't don't dispair - turn your back, set off a Pet Corrector, use a water pistol - any of the usual distraction methods will work but you must be consistant and do the same distraction every single time.