Dasei 67 Percent

This comedy manga takes place in a college girl named Yoshizawa's room. Her friends, Itou, Kitahara, and Nishida often stop by, and they run into funny adult-level problems. For instance, there is the day when her friends drop by while Yoshizawa's hungover in bed, and she suddenly realizes that she doesn't have on any underwear under the covers. Yoshizawa also has unusual problems, like her need for advice on drawing realistic penises in her manga, since she's never encountered one in real life before. There are a lot of quirky things that can happen in a college girl's home!

(Source: MangaHelpers)

Included one-shot:
Volume 2: Tama Ballistic Gelatin