The "plap plap plap" sound during sex is something that you hear only when either one of these two things happen:
>the female's buttocks slam against the male's hips
>the vagina 'queefs' because the penis can't completely fill it, thus creating space for air to come out
Also, telling someone to "get pregnant" does not actually increase the chances of pregnancy. With healthy semen, the chance of pregnancy should be nearly 100% with just one intercourse.
In other words, people who use this meme are basically confessing to having a small penis and low sperm count/motility.