The answer is relative to how large the phallus entering the anus is, compared to how often one engages in inter-anal intercourse. The sphincter is a muscle and can be conditioned to stretch if one partakes in too much anal sex.
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Your question is not specific but if you mean enlarge, it is not a good idea.
from baby gap
"In the butt" typically refers to anal sex. It is a colloquial expression that can be used humorously or to suggest engaging in this sexual activity.
None
Stick your fingers up your butt.
Rectum, Butt, or Bottom
Anal stimulation and pleasure.
no
It's the fin closest to the butt.
Yes, silkworms silk comes out of there anal opening-(there butt-hole)
They use butt plugs.