Is a Danish abbreviation which stands for 'sut min pik låh', which means 'suck my dick låh'. The word 'låh' has absolutely no meaning and it is merely an empty word. The abbreviation is commonly used by the Vietnamese society based in Denmark and can be used in many circumstances, especially if you have nothing more to say in a heated argument or just for fun.
Person 1: 'Damn you sister is hot'
Person 2: 'smp låh'
Person 1: 'It is going to be an awesome trip'
Person 2: 'I forgot my underpants smp låh!'