Singer Sheryl Crow has said a ban on using too much toilet paper should be introduced to help the environment.
The shows include a short set from Sheryl Crow and film clips
Crow has suggested using "only one square per restroom visit, except, of course, on those pesky occasions where two to three could be required".
The 45-year-old, who made the comments on her website, has just toured the US on a biodiesel-powered bus to raise awareness about climate change.
She teamed up with environmental activist Laurie David for the shows.
The pair targeted 11 university campuses to persuade students to help combat the world's environmental problems.
"I have spent the better part of this tour trying to come up with easy ways for us all to become a part of the solution to global warming," Crow wrote.
"Although my ideas are in the earliest stages of development, they are, in my mind, worth investigating.
"I propose a limitation be put on how many squares of toilet paper can be used in any one sitting."
The tour ended on Sunday at the George Washington University in Washington DC, where Crow performed with Tim McGraw, Faith Hill and Carole King.
David (left) and Crow have finished the Stop Global Warming College Tour
Laurie David's husband, Seinfeld creator Larry David, also appeared.
Crow has also commented on her website about how she thinks paper napkins "represent the height of wastefulness".
She has designed a clothing line with what she calls a "dining sleeve".
The sleeve is detachable and can be replaced with another "dining sleeve" after the diner has used it to wipe his or her mouth.
The shows involved a short set by the singer, a talk by David and segments of Al Gore's environmental film An Inconvenient Truth.