Being naked in front of brother/sister

Hi my name is simon im 14 years old and come from england. Last June it was my sisters birthday and my mum had gone on holiday but before she left she said because she wasnt gonna be there she'd leave her present there and let my sis have a sleep over. I invited my friend to sleep too called john age 14. at about 11 o'clock they shouted our names and asked us to go there. They= my sister (13), my nextdoor neighbor lauren (14), sarah (13), fran (13) and cahrlotte (14). So we go in and they lock the door we asked wat was goin on. Lauren said "we want you to strip now!" john fancied lauren so he said "ye ok we'll do it" i was shocked but did it. wen we were totaly naked lauren asked if she could feel our $%!@. she did before we anserd and we got erctions!