The “MAKE LOVE”/“NOT WAR” easter egg was in TECO for DEC PDP-6/10 machines. But DEC TECO was also ported to Multics, so maybe that was the Honeywell machine you used it on.

But, for a whole bunch of reasons, I’m left with the suspicion you may be misremembering something from the early 1970s as happening in the 1960s. While it isn’t totally impossible you had this experience in 1968 or 1969, a 1970s date would be much more historically probable