Murikuri

Murikuri (むりくり) is a one-shot manga by Clamp, published in Vol. 4/5 (a special double issue) of Kodansha's Young Magazine in 2002.

Plot
Murikuri is a series of short stories featuring aliens, a man conceiving a baby, and a pig. Many of these stories revolve around sexual desire. The first story involves a girl giving a love letter to a pig. His friend, a grade-school boy, envies the pig because of the pig's height, which allows him to see girl's panties. Another story is about aliens abducting a woman because they find her attractive. Yet another, is about a man discovering he's carrying a baby, which is an unwelcome surprise as it means he and his wife can no longer have sex.