Lance Bass -- There Has DEFINITELY Been a Gay President

Lance Bass isn't sure if he'll see a gay president in his lifetime, but he thinks there has definitely been a little same-sex lovin' in the Oval Office at some point.

Our photog caught up with Bass after his gig judging the Queen of the Universe Pageant and asked him the stereotypical gay-themed question (memo to photogs: Lance can talk about other things).

But the always-entertaining Bass made it fun ... saying the odds are at some time in history "someone in the White House has slept with the same sex."

He then jokingly added, "I'm looking at you, Roosevelt." Which raises the question ...