Khloe and Kris were out Wednesday in WeHo flanked by security as they hit up a couple of baby stores -- on account of the whole fam being in birthing mode. We asked Khloe if she and Tristan Thompson are going with a "K" baby name, and just then it happened -- the TMZ tour bus pulled up, shocking everyone on the scene.

Check out the vid ... we talked Kim and Madonna with Kris, who seemed to have a case of the giggles. Khloe was also amused when he talked about her Kardashian kid being a family record-setter.