Cum Volcano Erupts Without Stroking

My pulsing hardon tents in my underwear as I slip them down revealing my erect penis. I feel so horny I could cum at any moment. As sexy submissive fantasies play out in my mind, I put pressure on the base of my shaft and hold it. My rod swells as I feel a massive climax approaching. My cock convulses on it's own, shooting out ropes of cum, one after the other sliding down my shaft. An earth shattering orgasm!