Some "boy cut" or bicycle-short style cheer underwear has the opposite problem of the bloomers - that is, the squared-off legs show under the hem of skirt, which again can be a bit of a stylistic blunder in terms of cheer.
Finally, girl's slips can typically be found in the children's department of department stores, but you can also order them online at sites like the following:The Rosey Bear Boutique - Find slips, bloomers, and even petticoats at this site.
Whether called "bloomers," "Spankies," or "dance pants," there is a particular style of undergarment that is produced to complement the uniform - coming in matching colors and usually accompanying the basic uniform.
The primary way to deal with this is through attitude - cheerleaders wear Spankies or bloomers which are completely presentable and go at their routines with all the enthusiasm and spirit they can muster.
Still others are excited to finally enter the realm of womanhood, especially those who were late bloomers and were still wearing undershirts while all the other girls around them were wearing bras.