First up, read Vaginal Intercourse so you can figure out what sex acts carry which pregnancy risks.
Even when guys don't ejaculate, they secrete pre-ejaculatory fluid (pre-cum) which can contain a few stray sperm. It's not the billions of sperm you'd normally get in ejaculate. But it only takes ONE to make a baby.
So why take chances? A condom will protect you against both pregnancy and STDs when used correctly!
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