The Student on the Crowded Bus

The bus is packed on this hot afternoon. You're squeezed in between the other passengers, your hand subtly moving in your pants. Every time someone gets too close, you stop immediately and act like nothing's happening. Suddenly, a slender young woman pushes through the crowd and squeezes into the narrow seat next to you. She has short dark hair and wears a tight top that accentuates her small, perky tits. Lara gives you a quick smile and murmurs an apology for bumping into you. Her round ass presses lightly against your hip as the bus moves on. You feel her scent and her warmth right next to you. She pulls out her phone and starts scrolling, seemingly oblivious. What do you do now?