A great way to insult someone is to not acknowledge their existence. It's why maybe the ultimate burn in television history is Don Draper responding to Michael Ginsberg's, "I feel bad for you" by looking straight ahead and saying, "I don't think about you at all."

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Whether it was intentional or not, a couple of former Celtics had a slightly less dramatic and significantly less handsome version of the Draper-Ginsberg exchange.

On Tuesday, Ray Allen officially announced his retirement from the NBA. He hadn’t played since 2014, but guys around the league were probably aware that Allen hadn’t actually quit.

Naturally, his former teammates were asked to comment on Allen's news. Having played for four teams over a lengthy NBA career, Allen had plenty of teammates. None, however, could answer the question like Rajon Rondo.

Rajon Rondo on Ray Allen's retirement announcement: "I thought he'd been retired." — Sean Highkin (@highkin) November 1, 2016

In fairness, it could have been an honest mistake, but even if he didn’t know that Allen wasn’t retired, Rondo is a bright enough guy that he could have played it off by paying Allen a bunch of compliments the way everyone does when a player retires.

Rondo’s quip shouldn’t come as a massive surprise considering Paul Pierce admitted to Jackie MacMullan in 2015 that Rondo and Allen didn’t really like each other. In fact, Pierce said that Allen didn’t really have a strong relationship with anyone on those Celtics teams.

"It was a weird relationship,'' Pierce told MacMullan. "We were all good friends on the court, but Ray always did his own thing. That's just the way Ray was. Even when we were playing together, we'd be having a team dinner and Ray wouldn't show up. We'd go to his charity events but Ray wouldn't show up to somebody else's.

"I called him on it. I said, 'Man, Ray, we support all your stuff but when we ask you, you don't come to ours.' I remember when Rondo re-signed with Boston, we had a little dinner at a restaurant and Ray didn't show up.

"I know Ray probably didn't like Rondo that much, but it wasn't a fact of not liking somebody. You don't have to like everybody you play with -- it's a matter of showing support.

"Rondo probably didn't like Ray either, but he came to Ray's functions to show, 'Hey, we're together in this.'

"It's not a bad thing with Ray. We had a great relationship on the court. But even the year we won it, after a game we'd say, 'Let's go have something to eat and have a night with the older guys.' We'd get there and it would be me, Kevin and Sam (Cassell), but no Ray. In a lot of ways, me, Sam and Kevin were our Big Three.

"It just got to the point where it was, 'That's Ray.' No hard feelings. Everyone made such a big deal of us not talking after we left, but there really wasn't much there.''

After being acquired via trade during the 2007 NBA draft, Allen played five seasons for the Celtics, winning his first NBA title in the 2007-08. He departed for Miami following the 2011-12 season, winning his second and final championship the next year.