Pumping is the injection of silicone into tissue to literally "pump" it up. It's become very common among people who want cosmetic procedures but don't have money to go to an actual surgeon. Pumpers, who usually aren't doctors or nurses, offer "deals" to inject clients with medical-grade silicone for just a few hundred dollars. Instead, what clients get is industrial-grade silicone if they're lucky (often mixed with stuff like Crisco or baby oil), and the ill effects often aren't immediately apparent.
A few people have died from the procedure recently, and some also get infections, but for most things initially seem fine. Then, often years or even decades later, the silicone starts migrating downward into people's chests, legs, etc., hardening and causing extreme pain. This is just another good reason to be extremely leery of any "deals" when it comes to injectables, and always make sure that you're getting treated by a licensed, board-certified plastic surgeon.