Not to be taken seriously - these are daydreamed plans that concentrate on emphasising the absurd nature of their own suggestions. I really do have no intention of doing any of these!
Follow a complete stranger, documenting their movements with ridiculous detail, creating a log of the whole day activites, or for as long as it is possible to follow them. After the first experiment, take a camera and start to take pictures of the subject to add force to the documentation.
Spend a day in your normal intended activities for the whole day but imagine at all times that you are being followed. Imagine the reason that the person may be following you, imagine them writing down each of your actions in a notebook with meticulous detail. Try to think what they might be writing, write it down yourself. Imagine what your follower might look like, pay heed to what the sense of being watched closely does to your state of mind and your awareness of people around you.
Spend a day occupied with activities that are normal for the day, living each as you would normally do but this time imagine all the time that you are the only person that exists. Each other person must be seen as an actor that is playing the role that he/she has been designated, with the sole intention of fooling you into thinking that this is the real world and this is how life is lived. Imagine that every building that you see is not a solid, complete building but is a mere fašade, part of an exceedingly elaborate stage-scenery. Each building, each room, every single space that you enter is predetermined. Fate has already been written, down to the last detail. Imagine that you are going to attempt to foil the plan and deliberately do something that is unpredictable, to try to catch the actors or stage directors out. Would it be possible to enter a building that you were not supposed to want to enter only to find that it does not exist, that perhaps it is only a fašade.
Choose a day to spend in a town center and set an agenda to enter every single public place in that town in a methodical way. Each space must be entered in a specific order, but one that is invented at the time of approaching the first. Or criteria could be set for deciding which order to enter shops, for example, according to the first letter of their name or the colour of the bag in which they sell their merchandise. Document the experience of entering each shop, the smell that it has, the sounds that exist whilst you are there.
Be someone else for a day. Choose a name and a new identity. Dress as someone else, decide how you are going to behave, what sort of person you want to mimic, then take an overnight bag, catch a train to anywhere, stay the night in a hotel as them.
Drink only water for a day, having a measured amount every hour for twelve hours with no food. Intersperse this with other timed activities. Walk round the park the middle of each of these half-hours making sure that the route you follow is different each time. Jot down the route you take during or directly after each walk. Create a clear map of the timed walks, the times they took place and label any specific events that took place during that particular walk, or any observations that were made, or even any feelings that you had or entirely ir relevant personal thoughts. Then name each walk according to the notes that were made from it.
Create or find an object that floats well. Walk upstream from a river mouth, until you reach a bridge or loch. Place the object in the water and watch it float downstream as far as possible. Document its progress in detail and time its journey from the lock to the mouth and until you lose track or until it sinks. Perhaps enclose a message in the container or attached to the object, so that if someone we re to find it they will contact you so that you can record the journey.
Day of nostalgia. A whole day, at regular intervals, attempting through various means to recall things that happened to you in childhood, each memory should be recalled in as much detail as you can muster and then recorded in the way that is was experienced. Try to build up a catalogue of your past in fragments of memories. Link them to objects that are encountered on a daily basis so that these fragments of the past become present and exist in the every day world as a kind of alter-reality. Possible approaches; a series of scents, if the right scent is found, a memory may be triggered. Photographs from the family album, this is dangerous since the memories can often be invented around the photograph and around things that have been said by parents and relatives, thus record the memory and comment on the extent to which you think it may be true.