Try peanut butter and bananas on a sandwich. Lots of calories without the sugar from jam or jelly. Tastes good too, but you have to have some milk or water with it. Just remember, the roids won't do anything at all if you aren't getting the calories in. You need to keep your protein up as high as possible as well. Chicken breast dry seasoned with McCormick Steak seasoning is great. I just throw it on the Foreman for 9 or ten minutes. Good high protein snack. Fast food is high in calories but you sacrifice quality protein, and the fat is usually crazy.
To get in more calories, try not to drink while you eat regular meals. Water fills you up.

Keep your protein high! Protein powder, perhaps a mass gainer will be a must for you a nice high quality protein with lots of carbs.
For adding extra calories to my diet I love to add roasted almonds and a couple table spoons of extra virgin olive oil to my shakes.

Big bowl of spaghetti and meatballs or fettucini alfredo with shrimp. A high calorie snack u could have is supreme protein bars, each bar has over 400 calories.

whole chocolate milk, 16oz is a good way to add 440cal and 16g of protein to a meal.

chicken.... steak.... pizza.... shakes.... peanut butter and jelly sandmiches

peanut butter. ancient bodybuilder secret. shhh.

red meat. Yum

uhhh ..protein shakes mr bong