Good gift

I have a friend who is going to a foreign country for 4 years what would be a good gift to give him

I would give them something very small that would remind them of you, that would mean something to both of you like a picture of you two together.

One hundred billion dollars (holding hand to mouth with pinky).

If you don't have a hundred bill laying around, you might consider an appropriate power adapter.

you could get a shoe box and put little things in it like a few mini games like how they have at walmart, a couple snacks that maybe you both like, a small picture you have of the both of you, and whatever else you could think of

Some friends left the UK for the US and another friend made them a jokey reminder of all the foods they would miss in the US! It was a glass case with the sign 'break glass in emergency' on it, and it contained classic British foods (BIrd's custard powder, Cadbury's chocolate, Marmite etc) that they were unlikely to find abroad! It was a good joke and a thoughful gift, because they'd had to spend time making something rather than just buying a gift.