معنی روان It's too lumpy در جمله‌ی زیر چیه؟

A: Uh, Well, anyway, I can’t sleep in this bed. It’s too lumpy.
B: Too lumpy?
A: A lump! I don’t get it, a new mattress. Get off the bed for a
second. Why, it’s a piggy bank. What’s this doing under the mattress?