Well let's see, the song is from 1981 and the Vietnam memorial wasn't dedicated until 1982. And the lyrics are pretty obtuse. Seems to me it's more likely they were referring to the Berlin Wall?
Piss on the Wall
(Peter Wolf/Seth Justman) - 1981
Now some people think the world is what it ain't
To some I'm a sinner, to others a saint
Some folks say the world ain't what is is
All I know is I just got to take a wiz
Where am I goin' and where have I been
My head's in the clouds and my tail's in a spin
Jumpin' out of planes for the thrill of it all
Then I bounce back and take a Piss On The Wall
Politics - Shmolitics
They oughta save their breath
Mean streak - blue streak
They sentence me to death
Harangue me from a tree
Twist and shout until I crawl
Do the flip - do the flop
Piss On The Wall
Well the Yanks hate the Reds
And the Greeks hate the Turks
I really hate to say it
But they're all a bunch of jerks
Seems like everybody's shakin'
'Cause the big one's 'bout to fall
I'm just tryin' to hold it steady while I
Piss On The Wall
I can only remember the interview I watched on TV back in the early 80's that debated the "wall" in the song.
I never related the song to the memorial wall untill I saw that.
For those of us old enough to remember the late 70's, early 80's, lots of people protested the wall being built because they didn't like the war.
I can assure you 100%, Piss On the Wall was NOT about the Vietnam Memorial. Not only wasn't it even in the planning stages when the song was written, but they weren't sober enough to make that political statement then (I'm not kidding!).
The person who said it was about the Berlin Wall was correct.