Many meshes require a "pelvic hider" to remove the default avatar's texture so it doesn't "poke through" the 3D model.
Export your completed mesh as an file (IMVU’s proprietary mesh format). IMVU’s Create Mode Editor allows you to import Mesh .xmf and Texture assets to build products for sale in the catalog. Penis Mesh For IMVU
What or skin brand (e.g., Niramyth, Aesthetic) are you currently using? Many meshes require a "pelvic hider" to remove