The story I remember is he was giving a tour of Plains,GA to some middle east dignitaries. He had the limo pull over so he could letergo on the wall of a building on main st.
Billy Carter admitted he was a paid lobbyist for Libya. He made three trips to Libya. It was on one of these trips that it was reported he whizzed on the tarmac near the landing gear. A grainy telephoto image was published at the time (pre-internet) which caused much water cooler commentary.
Whether or not he repeated a performance on hi home turf while squiring visiting Libyan officials is beyond my recall.