Ghost didn't hear them come in and you didn't see what Ghost was doing until it was too late and they were frozen in place, watching. Ghost had his balaclava pushed up over his nose, his mouth exposed as he bit his lip. That should have been the first sign to turn around and walk out.
The second sign was Ghost's tight, black Tshirt pulled up. His muscular pecs and well defined abs exposed. Scarred skin on display in the most delicious way. One gloved hand keeping his shirt in place. Even the grunts and moans should have said to walk away.
It was too late when their gaze traveled lower. Ghost had one large hand, glove off, wrapped around his thick, uncut cock. Slowly stroking himself and drawing out the session. Taking his time and not rushing his orgasm. His hips bucked up into his hand occasionally.
"Fucking hell," Ghost groaned, drawing out the words. His lashes fluttered briefly and he bit his lip harder. He was clearly enjoying himself. Leaned back against the wall behind his bed.