A packer is something that resembles the male bulge in pants/shorts. So, a STP packer would be one that you can use the bathroom with and keep in your pants all day. A dildo is a sex toy that women and men can use to stimulate penetration when they are masterbation (or in some cases having sex).
Downs says her company created an awesome "pack and play" dildo, meaning it can be worn discreetly under clothing by wearing the dildo in a harness and tucking the shaft down between your legs. It...
"Dildos can be used during solo sex, partnered sex, multi-partnered sex, anal sex, vaginal sex, strap-on or pegging sex, and double-penetrative play," she explains. You can also use certain dildos to pack — aka create a bulge in the front of your pants or the illusion of a biological penis — stimulate a blow-job or hand-job, and more.
These types allowing the packer to simulate a flaccid position (if not a flaccid feel), as well as a very firm, erect position. Another term for packers which may be used for sex is packing dildo. A colloquial expression for the usage of these is pack and play. Slang