Loaded Question
The Fallacy
Asking a question that has an assumption built into it so that it can't be answered without appearing guilty.
Why it's wrong
Loaded question fallacies are particularly effective at derailing rational debates because of their inflammatory nature - the recipient of the loaded question is compelled to defend themselves and may appear flustered or not on the front foot.
Example
Grace and Helen were both romantically interested in Brad. One day, with Brad sitting within earshot, Grace asked in an inquisitive tone whether Helen was having any problems with a drug habit.