The most probable cause for bumps on the legs and buttocks is ingrown hair wherein the hair grows sideways, into the skin or it curls into the skin. This is a result of blocked pores or an accumulation of dead skin cells that hinder the proper growth of body hair. The ingrown hair may be accompanied by dark colored bumps, soreness, itchiness and an infection with pus, just below the skin. This condition can definitely be very irritating and discomforting especially due to its unattractiveness. Waxing and shaving are the primary causes for ingrown hair as the hair tends to break mid-way while doing so. Tight fitting clothing and friction can also cause the breakage of body hair. These bumps could also be a result of skin diseases like dermatitis. Excessive moisture or overactive sebaceous glands could also lead to the formation of ugly bumps on the skin. However, your query does not clearly state the characteristics of the bumps.
To prevent the formation of any kind of bumps on the skin, maintaining personal hygiene is of great importance. The use of a mild body wash is recommended so that the skin is not stripped of its natural moisturizing oils. Rubbing the skin gently, with circular movements of a loofah, is recommended for loosening ingrown hair. The loofah will also assist in removing any dead skin cells that may be responsible for blocking the pores of the skin. A body mask made with oatmeal, honey and a pinch of turmeric powder is also beneficial in the treatment of ingrown hair and skin ailments. Applying this mixture to the affected area and rubbing it off gently after 15-20 minutes will help in reducing the bumps. The oatmeal draws out the excess moisture and sebum and exfoliates the skin, honey kills germs and aids healing and turmeric powder reduces any discoloration of the skin while preventing the growth of unwanted hair. A final rinse with a mixture of warm water and aloe gel or tea tree oil will assist in killing infection causing germs. Wiping the skin thoroughly will ensure that the skin is completely dry, reducing the chances of infection. When the skin is wet, rubbing it with a towel, in the direction opposite to the growth of the hair, will help in reducing ingrowths. Immediately after drying your body, massaging the affected area with vitamin E oil or almond oil will help in nourishing and smoothening out the skin.