Like he will say it tickles and then goes down and it makes him really mad? Why does this happen sometimes?

How old is he... that matters a lot.

21

Is he on any medications like for high blood pressure or diabetes, depression? Has he had a complete physical lately? Stressful job?

Stressful job . Not on any meds and don't go to doctor unless something's wrong

Stress alone can do it... but he REALLY does need to get at least an annual physical. He needs to know if he is developing high blood pressure or diabetes. Neither have obvious symptoms. And both can kill you before you know you have them.

Even young guys can develop either or both. Even the tough guys that think they are invincible.

Always better to be safe than sorry. And once a year isn't a major inconvenience.

Every guy has that happen from time to time... even if they won't admit it.

He thinks that losing his erection is nothing wrong at the tender age of 21? Yeah, something's wrong. Time for the doctor.

He thinks that losing his erection is nothing wrong at the tender age of 21? Yeah, something's wrong. Time for the doctor.

One time occurrence isn't anything to worry about... but the more frequent it occurs and at a younger age 61 isn't the same as 21... THAT's a red flag.

Make sure its just mental exhaustion and not a medical issue by first seeing a doctor.

J_9 is in the Medical field. He really SHOULD make an appointment for both your pieces of mind.