“And the kings of the earth, and the great men, and the rich men, and the chief captains, and the mighty men, and every bondman, and every free man, hid themselves in the dens and in the rocks of the mountains; And said to the mountains and rocks, Fall on us, and hide us from the face of him that sitteth on the throne, and from the wrath of the Lamb:” (Rev 6:15-16)
These people (the lost who are alive at the Second Coming) are calling for mountains and rocks to fall on them. That would cause great physical injury and perhaps death. That they would rather be crushed by rocks than come face to face with God and the Lamb shows that the mental anguish would be far more painful than the physical.
The next verse says:
“For the great day of his wrath is come; and who shall be able to stand?” (Rev 6:17)
“To stand” is not referring to physically standing on two feet.
“But who may abide the day of his coming? and who shall stand when he appeareth? for he is like a refiner’s fire, and like fullers’ soap:” (Mal 3:2)
Malachi links the words “abide” and “stand” in the verse above. Joel uses “abide” in the same context.
“And the LORD shall utter his voice before his army: for his camp is very great: for he is strong that executeth his word: for the day of the LORD is great and very terrible; and who can abide it?” (Joel 2:11)
We sometimes say that we “can’t stand something.” That is the sense in which “to stand” is used here. People will be overwhelmed with the realization of their own sinfulness especially as they will be in the very presence of the Lamb Who died for them.
Whether saying “the wrath of the Lamb” indicates the lost correctly understand the truth about God’s “wrath” or not is unclear but clearly they wish to avoid coming face to face with the One they have rejected. This corresponds to the emotional state of the lost at the final judgment as described in Zech 14:12.