how do I get rid of the butter lumps- I rushed the butter and it was still cold---help!

Let it come up to room temp and whip it again, it should smooth out. HTH

Quick tip: Scoop out a cup of the icing and place in a plastic bowl then warm it up in the microwave for a half minute. Add warm icing to the lumpy icing and turn on the electric mixer. Done.

For next time, I learned a trick on here to soften butter quickly. You grate it on a cheese grater. Works great. You still have to give it a minute but nothing like true waiting time.