Is that so you can make chips ? 
The smokers club seems to think there is a lot of nicotine in potatoes. 
The nicotine contents of vegetables
After spending an extraordinarily long time figuring out exactly how much nicotine eggplants contained, I found a proper source and made this page to make Google more helpful in the future. The data is taken from the New England Journal of Medicine vol 329 p437, available here.
Vegetable Nicotine in ng/g g per 1µg nicotine
Cauliflower 16.8 59.5
Eggplant (Aubergine) 100.0 10
Potatoes 7.1 140
Green tomatoes 42.8 23.4
Ripe tomatoes 4.3 233.0
Pureed tomatoes 52.0 19.2
1µg of nicotine is the equivalent of sitting in a vaguely smoke filled room for three hours. A cigarette contains about 7mg of nicotine, of which 1mg is absorbed. In other words, 100g of eggplant contains 0.01mg of nicotine, and 10kg of eggplant is equivalent to one cigarette. However, absorbtion rates from ingestion are low and nicotine is quickly metabolised, so the effect isn't nearly the same.
