Yes. The instant you enter a modern gym, a 250 pound guy with muscles in his forehead latches on to your back.
Don't be alarmed.
He's what's known as a "spotter". During your workout the spotter will excrete large amounts of sweat from its thighs and crotch area. Spotter sweat contains large amounts of testosterone and steroids that works its way into your body so that you will also develop muscles in strange places.
It's acceptable to tip your spotter for their services, either in cash or raw meat.