This is the 9227th most frequent Portuguese word.
capotar
To overturn, flip, or roll over (usually referring to vehicles).
Here, 'capotar' is used to describe an accident where a vehicle overturns.
O carro capotou na curva por causa da velocidade.
The car overturned on the curve due to the speed.
In this context, 'capotar' is used figuratively to express extreme tiredness leading to collapsing onto a bed.
Estava tão cansado que parecia que ia capotar na cama.
I was so tired that I felt like I was going to pass out on the bed.
Here, 'capotar' is used metaphorically, expressing a strong emotional reaction causing a momentary loss of composure.