Not exactly Erotic Humor, but I didn't want to clog up General. I saw a real ad that said:
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"Microfiber Towel is made with super soft microfiber material so it won't irritate your skin and is ideal for those with sensitive skin. 7.87"x 7.87" (20x20cm) Microfiber Cloth - Perfect for Cleaning Your Device!"  
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And it won't irritate the skin on my device.

After watching porn, you can clean off your keyboard and monitor, then wipe your dick.

 
Just a high-tech cum rag.