The -P convention: turning a word into a question by appending the syllable "P"; from the LISP convention of appending the letter "P" to denote a predicate (a Boolean-values function). The question should expect a yes/no answer, though it needn't. (See T and NIL.) At dinnertime: "Foodp?"

In fact, they were so lame that many of the printing terminals lacked a question mark character. The P was used as a substitute for a ? because it was the closest visual substitution. And naturally, most of our messages were one or two words for economy. "FOODP" would print correctly on machines that couldn't print "FOOD?" Not everyone had a fancy glass terminal, so you had to assume the worst case scenario, and use "P" in case someone was on paper.

On a related note, to make it easier to count spaces in indented code, we would use a "b" character with a slash through it. So the teletype was print b, then back up a space by sending ^H, and then put a / through it.

It looked terrible, but got the job done. It used up a lot of ink, but the bosses were watching paper use, not ink.