This one is easy and can make things like grocery or other shopping fun.
Send your sub to the store with a list of things that you need (or better yet go with them so you can watch them get embarrassed by having to select things for purposes other than their mundane uses. You can find an interesting list on the pervertables section of this site.

The trick with this activity is to build up anticipation for what is going to happen when they get home.

Options

If you go together:

• Tell them to go get you a specific item and then tell them what you are going to use it on/for later. For example, “Honey can you please get me a cucumber about the size of my penis so I can fuck you with it later.”
• For a more vanilla option you can pick things out for each other.
• Pick the items yourself and walk up to them while they looking for something else put it in the cart and whisper to them what you are going to do with it later.
• Tell them an activity you have planned later such as impact play, sensation play, edging with objects, or restraint play and ask them to pick out a few objects that you can use for the activity.

When they are shopping by themselves:

• Give them a separate list that is labeled as the pick-up for play later list and have them purchase items on that list.
  • If you are into humiliation, you can have them pay for them separately and have them bagged separately. This is particularly appealing if all of the objects are phallic in nature.
  • If you are into extreme humiliation, you can have them ask for a clerk for each object or ask them to pick out an object to use in the bathroom (just make sure it is clean first or use a condom) This also works for a punishment idea.
• Ask them to pick out 5 items for the type of play you plan on engaging in.
  • For example 5 items used for impact or 5 items for sensation play
• Give them a list of types of play such as impact, sensation, restraint and have them pick out an item for each.
• Tell them to pick out 5 items used for play without telling them a type of play and see what they come home with.

You can use this way of shopping at almost any store. Consider what fun you can have at the grocery store, discount stores, Home Depot, or even larger shopping areas such as malls.

The idea behind this is to build anticipation and follow it through with an enjoyable activity for you both.