the tendency (usually attributed to lesbians) to become the same person. They start wearing the same outfits, doing everything together, essentially becoming the same person at the horror and disgust of their friends.
Alice: Have you seen Dana and Tanya, they are wearing the same outfit in similar colors.
Shane: must be the urge to merge.
the term used in the gay community for the presumed tendency lesbians have of quickly moving together after dating for a short period of time. See U-haul lesbian
Although not unique to lesbian couples, this behavior is stereotypically attributed to lesbians.
The comedian Lea DeLaria joked:
Q: What does a lesbian bring on the second date?
A: A U-haul.
The U-haul joke symbolizes the lesbian urge to merge.
When two lesbians get together, and almost instananeously become THE SAME FUCKING PERSON.
trumpet and jeni got dat baaaaad urge to merge lolololol111!
Hey honey, come over here, I gots the urge to merge!