How do you know when a guy is about to get on hard?

Answer 1

You can tell when a guy is on hard when their penis stands up in their pants and when their penis is hard

Answer 2

Physical signs that a guy is getting an erection may include increased blood flow leading to the penis becoming firmer and more erect, possibly visible through his clothing. He may also exhibit behaviors such as fidgeting or adjusting himself discreetly. It's important to remember that privacy and respect are crucial when observing or discussing such intimate matters.