Solution:

When a body is charged by rubbing, its weight may increase or decrease slightly because:

1. Gain of electrons (negative charge):
   • If the body gains electrons during the process, it becomes negatively charged.
   • Since electrons have mass ($9.1 \times 10^{-31} \, \text{kg}$), the body’s weight will increase slightly due to the addition of electrons.
2. Loss of electrons (positive charge):
   • If the body loses electrons during rubbing, it becomes positively charged.
   • The loss of electrons reduces the body's total mass, so its weight will decrease slightly.

Thus, depending on whether the body gains or loses electrons, its weight may increase or decrease slightly.