I was once playing with mains (220V) and got distracted on the phone with a friend. I literally took with each hand one cable (they were crocodile terminals) I just could not let go, the current makes impossible to let go. I reacted like 5 to 10 seconds later, by letting me fall backwards, which disconnected the leads from the plug. I was 15 or 16…

I should have gone to the hospital, but I didn’t.

So, I do bot say it is not dangerous, but it is not like it will kill you in 1ms.