Drax the Destroyer has a justifiable beef with Thanos in the comics. His wife was killed by the Mad Titan and his daughter was believed to be dead (but later revealed to be kidnapped). When Drax got a chance to exact some revenge on Thanos, both he and the Hulk got a powerful slap to the face.
Drax and the Hulk share many similarities. They're both hulking brutes who possess superhuman abilities that make them incredibly powerful. In the Infinity Gauntlet saga, Drax had a strikingly similar physique to Hulk, so when the two hulking figures got a chance to take down an Infinity Gauntlet-less Thanos, they jump at the chance. However, Thanos was prepared for them.
In Infinity Gauntlet #6 by Jim Starlin, Ron Lim, and Josef Rubinstein, Thanos' reign is coming to an end, as his daughter Nebula takes the Infinity Gauntlet. She heroically brings back half of existence with a single snap and is attacked by some of the most powerful cosmic beings in the galaxy. Eventually, the gauntlet falls into the hands of Adam Warlock. As the conflict ends, Hulk and Drax decide to try to take on Thanos. However, their attempt is immediately foiled by the supervillain as he slaps both of them to the ground.
Even without the Infinity Gauntlet, Thanos is one of the most powerful villains in the Marvel Universe. Hulk and Drax must have thought they had the upper hand, but quickly learned Thanos isn't a weakling. Slapping both the brutes to the ground is extremely impressive considering both Hulk and Drax's strength. While the slap occurs, Thanos activates a nuclear bomb in an effort to kill himself and the heroes fighting against him. However, Thor manages to throw him into space with Mjolnir as he explodes in the stars. The bomb ended Thanos' rule as he would be trapped in the Soul Stone after the explosion.
Decades later, Drax would eventually kill Thanos himself, but in this battle, his attempt to attack a weakened Thanos failed. He can sleep easily knowing that Hulk, one of the strongest heroes on Earth also took a walloping from the slap. The scene showed the Mad Titan's power isn't to be underestimated, even when Thanos doesn't have all the Infinity Stones. One wrong move and he'll slap a powerful hero like Drax or Hulk to the ground.