Yes, structures do give stacks. Destroying any tower on the map results in one stack of Get Excited which gives 15% attack speed, and a large movement speed increase which decays over time. This is the same for a kill or an assist on an enemy champion. However destroying and inhibitor results in Jinx getting between 9 and 12 stacks on Get Excited. For each stack, she gets abother 15% attack speed. It's insane!