To obtain drinks by means similar to theft. Generally refers to picking up half finished and unattended drinks from tables and the sides of bars. But also can mean the use of flirting to get drinks bought for you, as well as simple theft of drinks from persons too drunk/distracted to notice.
The name derives from the danger involved, as you could get a 'mine' (spiked drink)
Also known as minesweeping.
"You so shouldn't have minefielded last night, you were THIS close to being a rape statistic."
"Great minefielding last night! That fat girl was a total chump for buying you drinks!"