To "bottom out" is when
one is having sex and the penis reaches the cervix, or the top part of the vagina, and can go no deeper. This
can be referred to as "bottoming out," or in the past tense as "bottomed out."
It can be either painful
or pleasurable, depending on the girl and how extreme the bottoming out is.
Man, I was fucking this chick last night
and she told
me to stop cause my dick was so big I was bottoming out on her.