The Nixon appearance on Laugh In was the opener of the second season,
September 16th, 1968. Candidate Nixon turned to the camera, and said
"Sock
it to me?" in an episode where everyone in the cast, except Judy Carne
(who
was the "socked" girl in the first season) got hit with stuff after
saying
the line.

No, Nixon didn’t get hit with anything, not even the bucket of water.
He
was the last "sock it" reference, and the punch line to the running gag
for
the show. That’s why the line is in the form of a question. See?

According to the producer of the show, it took six takes before Nixon
could
deliver the line without sounding angry or offended.

According to one authority on the topic, "Hubert Humphrey had been
approached
by Laugh in to do a similar cameo bit, but after consulting with his
advisors, Humphrey turned the opportunity down as being beneath his
dignity."