This is an acronym originating in the Middletown, OH region. The acronym is based on the following: "Worst Sex I Ever Had. aka WSIEH.
Normally this term does not apply to sex where a sexually transmitted disease was newly obtained by one of the participants in the sex - but it could.
In casual conversation, WSIEH is normally also written in all upper-case letters signifying an over-exaggerated emphasis on this acronym carrying heavy importance.
She continued to cry during sex and ask me to stop, then start again. It was the WSIEH.