Various tools and filters let you distort the original shape of objects in different ways. For example, the wavy line on the bottom of the background object in the logo and on the letterhead was created by applying the Zig Zag distort filter to the straight edge.
Converting straight lines to zigzags
The Zig Zag filter adds anchor points to an existing line and then moves some of the points to the left of (or upward from) the line and some to the right of (or downward from) the line. You can specify the number of anchor points to create and the distance to move them. You can also choose whether to create smooth anchor points for a wavy line effect, or corner anchor points for a jagged line effect.
Original line, four corner ...