And Monday night was no exception, as the 21-year-old model flashed her bra by way of a black sheer dress.
Upton was all smiles as she posed for pics on the red carpet while attending the premiere of the HBO documentary Casting By in New York City.
The blond beauty was accompanied by Dancing With the Stars' Maksim Chmerkovskiy.
"The two did not want to be photographed together and did the best they could to avoid the cameras," a source tells E! News. "They left the event around midnight and went to Catch sushi bar, that turns into a club. The two partied until the early hours."
Despite their best efforts, though, the pair was nevertheless snapped in the back seat of a vehicle.
Meanwhile, an eyewitness inside Catch tells E! News, "They walked in holding hands. They weren't trying to hide the rumors they are together."
As for whether they actually are an item, a source recently told E! News that the two "are just good friends," while a second source (who is close with Chmerkovskiy) has "heard nothing about them dating."
Of course, we won't blame them if they really are!
—Reporting by Michelle Falls and Baker Machado