The erotic massage scene in Beirut is not overwhelming, to say the least. You might get a hand job if you’re lucky but don’t get your hopes up. You can take your chances with 7th Heaven (http://www.7thheaven.me/) at Jal El Dib, an area outside of Beirut, which is known for a few naughty establishments.
Kimantra Spa (https://www.kimantraspa.com/) at Uruguay street is another idea. They don’t advertise any erotic services so you’ll have to negotiate with your masseuse. Word is that a rub and tug goes for around $30. Some “super clubs” may also offer erotic massage services, but you better stick with escort agencies, which might have some skilled masseuses in their stable.