Just like "Fragile" or "This side up", this labeling will almost 100% guarantee that your parcel will be tossed, bounced, drop-kicked, and/or stomped upon by disgruntled/delinquent shipping-personnel during its entire journey from you to your intended recipient. Yep, I'm talking to YOU, USPS/UPS/FedEx!!! There --- I said it --- got it off my chest! :P
During the infamous "angry political activists shooting at passing semi-trucks" period back in the 80's, some truckers apparently resorted to painting their trailers with huge "Caution: explosives"-type signs to discourage nearby riflemen who would prefer not to get blown up themselves along with their intended targets. A cartoon in a magazine during that time showed two redneck 18-wheeler-drivers discussing a huge "WHAMMO DYNAMITE" label that the speaker has painted on the side of his van; the driver is saying something like, "Actually, I'm hauling dried prunes, but I feel a lot safer this way, rather than my having 'Handle with care' written on there instead."
When you use a common household item with a hard wooden handle like a broom to strike the ceiling of an apartment, in order to remind an upstairs neighbor that the noise they are making is loud and can be heard by others.
"They don't respect me, Susan – I had to pound the ceiling with a broom handle more than five times!"