OK, so I'm thirteen and have erections. My church group is going on a trip and we are staying in a hotel. It is two people per bed. I have erections during sleep, and I wake up with them. What do I do?
Also on this trip I'll be playing soccer. I want to get a cup, but I'm too embarassed to ask my mom, and my dad isn't in the picture.
Well, whoever you are sharing a bed with is in the same boat as you. All men have erections during sleep and they typically wake up with erections. For the trip, have a pair of light, loose shorts that do no have a fly, which you'll use for sleeping in. You can't stop the erections, but you can at least keep your penis from peeking out. When you wake up, don't jump straight out of bed in the morning. Wait for your erection to go down first -- it will eventually. You can also wear a long, baggy shirt that hangs down as additional cover.
When changing where others are present, change your shirt first so that it hangs down and covers your groin. Then change your pants and underwear. Another trick is to wrap a towel around your waist and change your underwear under the towel.
Tell your coach that you know the importance of wearing a cup in soccer, but you don't want ask your mom. Ask if he would send a letter home saying that a jock strap and cup is required for the trip. You can then just hand the coach's letter to your mom. Another alternative is to ask an uncle, grandfather, a trusted male at church, or even the coach, if they would help you get one because you don't want to go with your mom.
How can I buy one on my own without my mom knowing?
I don't know why it needs to be without your mom knowing. Eventually the jockstrap that holds the cup will need to be washed and she is likely to find out. I can understand being embarrassed to ask. I figured if you asked your uncle, he could talk to your mom for you.
But if you are willing to buy your own, it isn't that difficult. You need to know your waist size, which you can get from the tag on your underwear if you don't know it. It will be measured in inches, so it will be a number like 28 or a range like 30-34. Go down to a WalMart or any other store that sells athletic equipment.
Look for a jock strap that includes a pouch that is near your waist size. Since straps have elastic waist bands, they are measured in ranges, such as 27-30 inch waists. Since you are probably still growing, avoid getting a strap where your waist is at the top end of the range. For example, if you have a 28 inch waist and your choice is a 26-28 strap or a 28-30 strap, get the latter one as it has more give and will last you a while during your growth.
The cups might be sold separately from the jock strap. The ones with some vent holes are a bit better than the solid ones. I've notice that cup sizes are always called large or extra large, no matter how big they are. Men refuse to think of their genitals as being medium or small for some reason. You will probably have to guess at the correct size -- there is no consistent measurement standard for cups. What you are looking for is one that will contain your penis and testicles, but without being so large that the edges of the cup ride on your thighs. I have found the cups in many stores to be basically all the same size, no matter how they are labeled. Getting a cup that is too big will cause your inside thighs to get irritated from the cup rubbing on them, so when in doubt, go for the smaller size. Too small of a cup carries the risk of the edge pushing on a testicle when you are hit in the groin -- the very thing you wear a cup to avoid.