Last week -It wasn't tough for Britney Spears to decide to reprise her role as ditzy receptionist Abby on CBS' How I Met Your Mother.

"I had such a great experience the last time I was on the show that I couldn't wait to come back," the singer said in a statement Monday. "I was really looking forward to working with this cast and crew again.

"Everyone was so nice," she added. "Abby is going to have a…