The massive hillside figure in Dorset -- which measures about 180 feet in length -- got a makeover recently that reflects these crazy times ... with some prankster getting up there and etching out a face covering for the big bloke to show he's heeding government guidelines.

It's pretty funny, 'cause his excited genitals remain uncovered -- as they have been for decades, if not centuries now. Gotta get that mask on though. According to one local resident, who spoke to the BBC, the new change has actually lifted the townsfolk's spirits, which we can all use right about now with stay-at-home orders.

It's unclear who defaced the blocked-off protected site, but The National Trust (which maintains and manages this thing) has said it does NOT encourage this ... though it's been done countless times in the past.

Once, the giant's twig and berries were adorned with flower petals and made to look like a plant, and another time ... it was tweaked to resemble a tennis racket.

Supposedly, this thing is off-limits to the public -- but, obviously, people find a way to get up there and screw around. Compared to the States, CAG's like our Hollywood sign, which itself has been vandalized and played with over the years -- to the chagrin of authorities.

As for what the hell the drawing, if you will, even is or where it came from -- well, it's a bit of a mystery scientists are still trying to solve. Some have speculated it originated during the Iron Age (back in BC times) but more likely, it's a bit more recent ... probably 17th or 18th century, as some experts have theorized it was initially done as political satire.

Whatever the case, people have kept it up for a long time now -- re-digging the trenches along the hill it covers, and filling it in with lots o' crushed chalk ... which gives it the white look.