Almost always, unless the man is older, and more in control.
Older, or rather more mature, experienced men are very good at their control, and give little warning.
There is always the twitch and swelling, but this varies from man to man.

Orally

Wicked Wanda

__________________
"I wondered, am I a lesbian, am I straight, or bisexual? Then I realized that I am just a slut.
So where's MY parade?"

---Margaret Cho